Dark Depths enters with ten ice counters on it.
{3}: Remove an ice counter from Dark Depths.
When Dark Depths has no ice counters on it, sacrifice it. If you do, create Marit Lage, a legendary 20/20 black Avatar creature token with flying and indestructible.
Given the rarity and limited information on some bonus cards, this may not be a complete list of all potential bonus cards available in this Secret Lair.
Killer Rabbit of Caerbannog (Kezzerdrix)
$5.54
First strike
At the beginning of your upkeep, if your opponents control no creatures, this creature deals 4 damage to you.