Spirit

Contortionist

At the beginning of your upkeep, you may fold this token in half.

Contortionist // Contortionist

Goblin

Kor Warrior

Elemental

Blood

{1}, {T}, Discard a card, Sacrifice this artifact: Draw a card.

Bird Illusion

Wolf

Wurm

Warrior

Shapeshifter

Phyrexian Goblin

Eldrazi Scion

Treasure

{T}, Sacrifice this token: Add one mana of any color.

The Initiative

Whenever one or more creatures a player controls deal combat damage to you, that player takes the initiative.
Whenever you take the initiative and at the beginning of your upkeep, venture into Undercity. (If you're in a dungeon, advance to the next room. If you're not, enter Undercity. You can take the initiative even if you already have it.)

Undercity

You can't enter this dungeon unless you "venture into Undercity."
Secret Entrance — Search your library for a basic land card, reveal it, put it into your hand, then shuffle. (Leads to: Forge, Lost Well)
Forge — Put two +1/+1 counters on target creature. (Leads to: Trap!, Arena)
Lost Well — Scry 2. (Leads to: Arena, Stash)
Trap! — Target player loses 5 life. (Leads to: Archives)
Arena — Goad target creature. (Leads to: Archives, Catacombs)
Stash — Create a Treasure token. (Leads to: Catacombs)
Archives — Draw a card. (Leads to: Throne of the Dead Three)
Catacombs — Create a 4/1 black Skeleton creature token with menace. (Leads 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.

Undercity // The Initiative

Assembly-Worker

Zombie

Human Soldier

Wizard

{1}, Sacrifice this creature: Counter target noncreature spell unless its controller pays {1}.