Badon, The Emerald Scaled

Flying, trample, hexproof from instants
As long as you control at least seven permanents
with counters on them, Badon has indestructible.
Whenever a dragon you control attacks, choose
one that hasn't been chosen yet this turn —
• You may play seven additional lands this turn.
• Sacrifice a planeswalker, then draw seven cards.
• Proliferate seven times.