The biggest thing with this game is playing solo is half the game. There are plenty of combos to do with heroes which is almost impossible on solo.
Tryande isn't that easy to play but she's good, her owl is great for vision and has great synergy with Diablo. Her stun, his charge and ability to flip the enemy towards your team. Her 20% extra damage skill is great.
Diablo also works well with zagara, zeratul because they can lock enemies in place and he can follow up with apocalypse.
I don't mind losing when playing as a team, solo can be just a headache though