
When Bumi enters, earthbend 1. (Target land you control becomes a 0/0 creature with haste that's still a land. Put a +1/+1 counter on it. When it dies or is exiled, return it to the battlefield tapped.) Whenever Bumi attacks, put two +1/+1 counters on each land creature you control.
How do you want this deck to play?
What the commander does best.
Every land you drop is a threat: animate the ground, then watch the whole continent march.
426 cards fit this theme
Stack +1/+1 counters, double them, and proliferate until every creature is a modified giant.
789 cards fit this theme
Swing with everything: attack triggers, trample and pump turn bloated land creatures into a crushing avalanche.
276 cards fit this theme
Off the beaten path, but they work.
Fill the royal court with Humans and legends, and let Bumi lead his noble allies into battle.
287 cards fit this theme
Flicker Bumi and friends so every enter-the-battlefield trigger animates another land and repeats the earthbend.
539 cards fit this theme
Sacrifice your earthbent lands for value and let them crawl back from the grave, tapped and angry.
126 cards fit this theme