Piru, the Volatile With Piru, the Volatile around, you can opt to pay the mana and keep a 7/7 flying and lifelink dragon around, or let it die to deal 7 damage to each nonlegendary creature
Yes, treasure tokens enter the battlefield and trigger ETB effects based on their traits like artifacts or tokens
Four mana for a 2/4 reach Deathtouch is already pretty decent, but then it also has a way to fix your mana on top
Adding the age counter and requiring the upkeep cost happens on the same trigger
Synergies : Cards that grant additional strength and/or willpower, evasive, or the ability to bounce Hades back to hand to replay
Banning Hiram slows Sapphire decks down in the mid-game by lowering the consistency of the item-return play