Bu Juan, Monument Builder

Whenever a nontoken artifact enters the
battlefield under your control, put a +1/+1
counter on Bu Juan, Monument Builder and
you gain 1 life.
Reveal an artifact card from your hand with mana
value greater than Bu Juan, Monument Builder's
power: Bu Juan, Monument Builder gains
indestructible until end of turn. Add {c}. Spend
this mana only to cast artifact spells.
Activate this only once each turn.