Lim-Dûl's Paladin

Trample
During your upkeep, you may discard a card. If you don't, sacrifice Lim-Dul's Paladin and draw a card.
Whenever Lim-Dul's Paladin becomes blocked, it gains +6/+3 until end of turn.
Whenever Lim-Dul's Paladin attacks and isn't blocked, it assigns no combat damage and the defending player loses 4 life.