Slark would do ulti and kill him easily and void would do ulti(none focus the bear) troll would do miss and lone won't attack probably(bash) and bear is missing a lot.Still it depends on a lot of thing,it would be cool if anyone could do a video about this(with perfect items)
Honestly, it all comes down to how do you build it. Pretty much any build has it's counter.But if you want sylla, consider 2 abyssals for some sexy triple bash action (counting entangle in). Maybe even repace one tarrasque with bloodstone, so your bear had mana too, for more.... umm... stunning performance.But then there's that hex-aghanim-refresher void with MoM and some divines, that can get you pinned down for some 20 seconds straight, which is enough to bring down most targets but mass tarrasque Cent or Spectre. These would however have hard time against aga-veil-eb-dagon5 huskar, if you filled him also with bkb, satanic, tarrasque, divines, whatever you feel up to in given situation. But then wild n'aix appears and blocks huskars combo with just rage, then kills him easily etc...Kinda tic-taca-toe situation. You can't simply get one build that kills everything.