I'm in Inferno now, I love to use my Hydra it helps me do damage as i kite. I can be running away with my back turned while the Hydra is still dealing damage. Its awesome. Arcane hydra is good for AoE damage but Venom is by far better, It dose damage over time and also leaves a posion pool on the floor so the longer enemy's stand on it the more damage they take
Poison, it does INSANE amounts of dmg. And yes, it obv stacks. Which may or may not be working as intended. I feel like they would have done something about it tho if it wasn't.