Undercity
Secret Entrance - Search your library for a basic land card, reveal it, put it into your hand, then shuffle. (To Forge or Lost well)
Forge - Put two +1/+1 counters on target creature. (To Trap! or Arena)
Lost Well - Scry 2 (To Arena or Stash)
Trap! - Target player loses 5 life. (To Archives)
Arena - Goad target creature. (To Archives or Catacombs)
Stash - Create a Treasure token. (To Catacombs)
Archives - Draw a card. (To Throne of the Dead Three)
Catacombs - Create a 4/1 Skeleton creature with menace. (To Throne of the Dead Three)
Throne of the Dead Three - Reveal the top ten cards of your library. Put a creature card from among them onto the battlefield with three +1/+1 counters on it. It gains hexproof until your next turn. Then shuffle.