Aether Fleet Captain

Dethrone (Whenever this creature attacks the player
with the most life or tied for most life, put a +1/+1
counter on it.)
Other Pirates you control get +1/+1 and have Dethrone
At the beginning of your end step, create X
colorless Treasure artifact tokens with "{t},
Sacrifice this artifact: Add one mana of any color
to your mana pool." Where X is the number of opponents with less life than you