Ebonblade Reaper [Onslaught] Vampyre Yavimaya's Avatar gets +1/+1 for

Yavimaya's Avatar gets +1/+1 for each land you control and each land card in your graveyard

Ultimate Sacrifice — {1}{U}

"The trick is

you may play 1 [Kiriha Aonuma] from your hand without paying its play cost

but for honor

Ebonblade Reaper [Onslaught] Vampyre Yavimaya's Avatar gets +1/+1 forSet: Onslaught Type: Creature Human Cleric Rarity: Rare Cost: {2}{B} Whenever Ebonblade Reaper attacks, you lose half your life, rounded up. Whenever Ebonblade Reaper deals combat damage to a player, that player loses half their life, rounded up. Morph {3}{B}{B} (You may cast this card face down as a 2 2 creature for {3}. Turn it face up any time for its morph cost.)