Yellow Diamond

: Whenever you put one or more loyalty counters on a planeswalker, amass Gems 1.
+1: Discard any number of cards. For each land card discarded this way, create a Treasure token. For each other card discarded this way, draw a card.
-3: This deals 4 damage to target creature or planeswalker. Then proliferate X times, where X is the excess damage dealt this way.