Myr Moonvessel

'Dies' means 'put into a graveyard from the battlefield.' If a creature is exiled instead of dying (Swords to Plowshares, Rest in Peace), dies triggers won't fire. Tokens do trigger 'dies' abilities briefly before ceasing to exist.

If this card's activated ability produces mana and doesn't target, it's a mana ability. Mana abilities resolve immediately without using the stack — opponents can't respond to them. However, abilities that target (even if they produce mana) aren't mana abilities.