I'm surprised I don't really see a lot of Sylla players, especially when there are so many ways to play him. Hopefully some of you will try these out and have fun!

So here's a list of possible ways to play Sylla: Not all builds here are equally efficient. Some are situational, while others are counters.
Dual Bear - tank-DPS melee
Dual Bear - DPS range.
Dual Bear - Pusher, lane controller
Sylla Only - DPS
Sylla Only - tank
Bear Only - Harasser, Global, Pusher, Lane Controller.
Hero Guide to Syllabear (tank-DPS melee)
This is the standard fundamental style of playing this hero. It incorporates all his skills with items that match his abilities. However, with 12 item slots, there is still a lot of room for preference and situational. I will provide a standard start up and then explain why certain items are recommended.
Early game, you start with Sylla and bear. You want to get boots and poison orbs for both. RoB is good as they share the aura, but the item goes on Sylla and do not upgrade it in case you want a vlad. From here, you want to upgrade bear's boot to tread so he gets the 30 IAS to increase chance of root. You save Sylla's boot for later BoT upgrade, b/c in bear form Sylla loses a lot of movement. It is recommended you get a pt booster early for Sylla especially if you wish to use him to remain range for a while.
So the 1st core item recommendation is cuirass. However, how you build cuirass matters. If you are doing well, farm that hyperstone and give it to your bear. Increasing the bear's IAS increases chance of root. If you are not doing well, get the plate and chain mail first. It is recommended putting the plate on Sylla and chain on the bear. Bear is naturally tankier early, so the minor amour helps while Sylla can benefit from the stronger armor. By this time, you can either finish the cuirass and give it to Sylla or don't finish it and leave the items separated. Finish the skadi on Sylla first instead. As you probably picked up by now, I always recommend skadi over heart, especially for an agil tank.
At this point, you are already buff enough and you can consider damage. Get a basher for EACH. This is what makes this hero so dangerous - 2 bash + 1 root.
So summarize at this point: Bear - tread + basher, Sylla - Boot (BoT), skadi, basher, RoB, cuirass
At this point forward, it really depends on the game and whatever your preference. Remember, most items should go on Sylla first before bear. If bear dies, Sylla can keep fighting.
Vlad - Vlad is good b/c both bear and Sylla share the lifesteal. You can get this earlier if you want and it helps you farm and fight. However, to be a real threat lategame, you want to get a satanic to stack that skadi. You can actually get both if you want, but it is redundant as you can get other items.
Drum - It increases movement speed for both Sylla and bear. It is a good early item, but you might not want it lategame.
SnY - I wouldn't recommend it b/c you get plenty of movement with your rabid + BoT. You also have skadi to slow and 2 bashers + root.
Butterfly - Always recommended for agil heroes, especially agil tank. It is a lategame item, so definitely recommend.
Final item recommendation for Sylla - BoT, skadi, cuirass, basher/abyssal, butterfly, satanic
Final item recommendation for bear - Tread, poison orb, basher (anything you want after filling up Sylla's items, you can even get support items to support your Sylla.)
There really isn't much strategy as you just bulldoze your way through anything. You can tank, you can kill, you can do just about everything. Watch out for WD or Lich.
Skillwise - level bear first then rest whichever you want, get ult along the way.
Hero Guide to Syllabear (DPS Range)
Now DPS range is similar to tank-DPS melee, with the exception of a few items. It is less "fundamental" as you do not use his ult. Essentially, you are playing 2 heroes, 1 tank and 1 range DPS. In this build you want to split items more evenly, though still favoring Sylla over the bear.
I still recommend cuirass first as it shares IAS and armor. However, you may want to put the item on the bear this time since you want him to have more armor to tank. Your hero still wants skadi so it helps you slow your opponent while 2 of you chase it down. Since in Sylla form, your hero moves faster, you may want tread for most of the game and it gives you that IAS.
From this point forward, you want to build Sylla hero as a DPS range. You can get lothar if you wish to flank. However, unlike other range heroes, you will always have a tank to back you up so you might not need it. You probably don't need satanic, instead get a mjolnir and cast it on the bear to tank. I would still recommend butterfly, but your damage item can either remain abyssal or get a crit or mkb instead. Now some players I've seen gets radiance for the bear to harass while tanking. I don't recommend this at all b/c radiance is a really expensive item and getting it early is bad unless you have a specific reason to get it.
Final item recommendation for Sylla - Tread (BoT), skadi, mjolnir, butterfly, Crit, Abyssal (last 2 items can be swapped out for situational or any other range DPS items you like.)
Final item recommendation for bear - Tread, cuirass, basher, poison orb (any other tank items after finishing Sylla first, just remember he doesn't benefit from stats so you want to get VG, soulbooster, shiva, etc...)
So you play the bear as the tank and Sylla as the DPS. Cast the mjolnir on the bear and let him lead. If you have lothar, you can position yourself in flank and use the bear to lure. etc..
Skillwise - level bear first then rest whichever you want, however skip the ult and get +2.
Hero Guide to Syllabear (Pusher)
Now I actually love this build, though it does get some use to. Your teammates may be confused at first, but they'll get it once you start doing your thing. Having 2 units with slots allow you to double certain push items, namely? Book!

Start off with just boots for both. You don't need tread for bear, however eventually you'll need BoT for Sylla to push. Rush level 1 book for both first, instead of leveling 1 of them to 3. This way you can cast them both and have 4 level 1 necros. Then finish and level both to 3 and you will have 2 level 3 books. This is a nightmare for your enemies, as again people underestimate book. This is not just good for pushing, but good for attacking.
Your next items are 2 manta, one for each. Yes, the bear can cast manta. Now why this works is that battlecry will work on all your units including necros and manta. I don't think rabid does, but I might be wrong. Usually this is as far as I get and enough to win the game. But should you need more, you can always consider a radiance and mjolnir to kill creeps fast. A vlad in this case would be great and cuirass will armor and increase IAS of all your necromons and images. This is a very scary build for your enemies and you can literally just suicide raxes. You'll get so much gold anyways it doesn't matter if you die.
Final item recommendation for Sylla - BoT, book 3, manta (then if the game is still going - vlad, cuirass, drum)
Final item recommendation for bear - boot, book 3, manta (then if the game is still going, radiance, shiva, etc...)
Hero Guide to Syllabear (Sylla only DPS)
Now this is a counter build, for when they picked a WD or Lich after you picked Sylla. It is not as effective and definitely not fundamental, but it does work and I have actually tried it. There is some logic to it in sense why it works, but again it is up to the player.
You start with Sylla, don't get bear. You level rabid and synergy. Synergy actually increases the duration of rabid. You don't get your ult. You get +2 instead. You can actually skip synergy if you like and get +2 instead. Don't underestimate +2, 5 level of those is like a free ultimate orb.
Like all range DPS, I recommend lothar for flanking. You keep rabid on yourself all game to give you the increase movement and IAS. Get tread as boots. Now, I actually would recommend SnY/manta, though you can skip it. The reason is the same for both yes or no. Your rabid gives you movement speed, so you don't need it. But your rabid gives you movement speed, so it stacks on it nicely. Since you only have 1 ability, might as well build upon it and increase your movement and IAS. After this, you can get your first damage item, which I recommend a crit. From here if you want a little more bulk and IAS, again get skadi. Then you can consider another weapon or get a butterfly/cuirass, etc.. If you want to be a little tankier, get satanic.
Just play him like any other DPS. Flank your enemies, defend your tanks. But with SnY or manta, you move extremely fast to get out trouble.
Final item recommendation for Sylla - Tread, Lothar, SnY/manta, Buriza, Skadi, butterfly/cuirass
Final item recommendation for bear -

Hero Guide to Syllabear (Sylla only Tank)
I actually don't expect anyone to try this build. Again it is not fundamental b/c you only build upon 1 skill. But likewise it is a counter build if their team counter picked Sylla or you need an "early" tank. Sylla can be an effective tank b/c of the HP gain from his ult and you sacrifice his 3 skills for the +2, essentially getting a free ultimate orb. So you build this as a straight up tank.
The ONLY skill you get is the ult, getting +2 for everything else. It sounds silly, but 5 levels of +2 is a free ultimate orb by the time you get your ult. Then you just keep stacking +2 with each level. Your item choices start with boot and change to str tread, then BM, then whatever tank items you want - BM, heart, satanic, skadi, shiva, mjolnir, etc...
By late game though, you will still have researched your other abilities including rabid and synergy. So you still can tank via DPS and IAS such as skadi + satanic. However, you choose your items base on the flow of the game, you may not need satanic if you were able to successfully tank earlier.
The question people ask is, "Can't this be done with any hero?" Theoretically yes, but what makes it work for Sylla is his ult's HP gain + the stats gain. Also his ult is permanent, not time limited. It is able to be tanky early and quickly. By lategame, he really is just like any other tank. So this is mainly when you need a strong tank in the early stage of the game.
Final item recommendation for Sylla - Tread, BM, VG for start and sell for skadi, satanic, butterfly, cuirass
Final item recommendation for bear -

Hero Guide to Syllabear (Bear Only)
Before you cringe, I ask you to give this a chance. I know there are a lot of ruiners that screwed this build, but this build is actually in my opinion the best build and my favorite, though it is not a fundamental build. Most definitely I do not recommend a dagon. I use to play this build so much, I had a account devoted to it called Ped0bear.

The purpose of this build is not to steal kills with a dagon. The build is a global controller, lane controller, harasser, pusher, etc... all in one. This is why the items must reflect maximum AOE potential and not just getting dagon kills. I pretty much never get dagon.
First, you get a boot for Sylla and you rush that radiance by 15 minutes. Then you put the radiance and boot on the bear and leave Sylla at base. You level bear first follow by 1 level of rabid and then synergy first. Synergy increases the duration of rabid. You can skip his ult if you like, but I usually get it b/c I cannot farm the radiance before level 6 and bear mode helps you neutral. Also, if they have Spec or Zeus, lategame they can kill your hero at the fountain if you don't have ult.
Now with radiance, you farm creeps by going into lanes, but more so you "redirect" creeps by pulling them away. You also harass enemy heroes to disrupt them from farming. Even if you don't get a kill, they have to TP to heal or just run. In team fights, you tank b/c the bear is tanky early.
Your 1st core item is BoT, this allows you to TP to lanes to push and control. It also increases your chance of evasion if enemy decides to wack you. Remember to keep rabid on so your bear can move fast. If the enemy attacks you often, you might want to consider a BM next to keep them off. However, most times you can just run into fog and recall back to base. Your worse nightmare are slowers, not disablers. Disablers you can evade, but multiple slowers... they can kill you quite easily if they are DPS. PA and Drows and maybe snipers will require you to get a BM.
Now whether or not you get a BM, your core after BoT is situational. It is either a mjolnir or Book. The preference is mjolnir as it makes your bear a complete nightmare to the enemy during team pushes. I've had games where my team farmed while waiting for my mjolnir. Once I have it, we bulldoze through mid and rax immediately. I got 4 kills off mjolnir alone.
However, book is also good and it is preferred when they have invisible heroes. Book can also allow you to skip BM. When a Drow is wacking me, I launch the necromons at her. Necro + radiance is instant kill on early weak heroes, the prey becomes the hunter. You chase them down.
After this point, it is completely up to you and the game. A guinsoo is always appreciated by your teammates but you can also increase your tanking ability with a shiva. You can even get a cuirass! It increase the armor and IAS of your allies as well as necros if you have book.
This is the one build which actually increases my APM when I play, I end up in the "zone" where I don't think anymore, everything is muscle memory and just controlling the map. I love this build, but I don't play it much b/c people complain about it from both sides. However, like the support Treant, I have a high 90% win rate with this build.
Final item recommendation for Sylla -

Final item recommendation for bear - Radiance, BoT, Mjolnir, Book, Shiva, cuirass. (You can also supplement for BM, guinsoo, dagon, etc...)
Remember, your job is to control the lanes, TP to push etc... and in teamfights, you tank and support. His "recall" works like Tinker, where if you are low during a team push, you recall back and heal, then return with BoT. Likewise, if the bear is killed, instantly respawn him and continue. This is why he is so cheap. You have to essentially kill the bear twice to make Sylla player wait for CD.
Conclusion:
OMG! That is a lot of different playing styles and roles! Is this hero FUN or what!??!
