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If you would roll a die, instead roll two of those dice and ignore one of those results.

Six-y Beast

As Six-y Beast enters, you secretly put six or fewer +1/+1 counters on it, then an opponent guesses the number of counters. If that player guesses right, sacrifice Six-y Beast after it enters.

Scissors Lizard

Creatures named Paper Tiger can't attack or block.

Painiac

At the beginning of your upkeep, roll a six-sided die. Painiac gets +X/+0 until end of turn, where X is the result.

Boomstacker

As Boomstacker enters and whenever it attacks, stack two dice on top of it. (All dice must be stacked vertically, one on top of another.)
Boomstacker gets +1/+1 for each die in its stack.
Boomstacker attacks each combat if able.
When the stack falls, sacrifice Boomstacker.

Infinity Elemental

Strategy, Schmategy

Roll a six-sided die. Strategy, Schmategy has the indicated effect.
1 — Do nothing.
2 — Destroy all artifacts.
3 — Destroy all lands.
4 — Strategy, Schmategy deals 3 damage to each creature and each player.
5 — Each player discards their hand and draws seven cards.
6 — Repeat this process two more times.

Blast from the Past

Madness {R}, cycling {1}{R}, kicker {2}{R}, flashback {3}{R}, buyback {4}{R}
Blast from the Past deals 2 damage to any target. If this spell was kicked, create a 1/1 red Goblin creature token.

Goblin S.W.A.T. Team

Say "Goblin S.W.A.T. Team": Put a +1/+1 counter on Goblin S.W.A.T. Team unless an opponent swats the table within five seconds. Activate only once each turn.

Goblin Haberdasher

Menace (This creature can't be blocked except by two or more creatures.)
Other creatures you control wearing hats in their art have menace.

Stet, Draconic Proofreader

Flying
Whenever Stet, Draconic Proofreader attacks, you may exile a card from your graveyard. When you do, Stet, Draconic Proofreader deals 4 damage to any target whose name begins with the same letter as the exiled card.
{W}: Delete the first letter of target permanent or player's name until end of turn.

Mountain

Super-Duper Death Ray

Trample (This spell can deal excess damage to its target's controller.)
Super-Duper Death Ray deals 4 damage to target creature.

Underdome

{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to pay Un-costs.

Pointy Finger of Doom

{3}, {T}: Spin Pointy Finger of Doom in the middle of the table so that it rotates completely at least once, then destroy the closest permanent the finger points to.

Abstract Iguanart

Whenever you cast a spell, note the first letter of its artist's name. If that letter wasn't already noted, put a +1/+1 counter on Abstract Iguanart.

Yet Another Aether Vortex

All creatures have haste.
Players play with the top card of their libraries revealed.
Noninstant, nonsorcery cards on top of a library are on the battlefield under their owner's control in addition to being in that library.

Goblin Tutor

Roll a six-sided die. If you roll a 1, Goblin Tutor has no effect. Otherwise, search your library for the indicated card, reveal it, put it into your hand, then shuffle.
2 — A card named Goblin Tutor
3 — An enchantment
4 — An artifact
5 — A creature
6 — An instant or sorcery