There is a big difference between a taunt ability and just regular taunts/tbagging. Dota has emotes yes, but dota also has Axe, so i don`t get your point about replacing an ability with just cosmetic animations.
That might be the best option, force your hero to follow and attack the hero who taunted you, but don`t lock the camera movement. Sort of like how the pause works in the game
Pretty much no one except geist ult heals that much HP in such a short window(just 8s), so even if it did hit multiple targets it doesn't matter, epecially considering that healing was nerfed globally. Such an expensive item needs to be strong by itself instead of requiring some quirky synergy...
Still weak. If the item requires a combo with a teammate or another expensive item it is just not worth it. The healing is not even that good. Just buy boundless + spirit burn instead of this item + Spirit Burn, it will give a lot more regen + extra spirit power