Krark's Other Thumb

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

The Space Family Goblinson

The Space Family Goblinson has trample as long as you've rolled three or more dice this turn.
Whenever you roll a die, put a +1/+1 counter on The Space Family Goblinson.

Molten Birth

Create two 1/1 red Elemental creature tokens, then flip a coin. If you win the flip, return Molten Birth to its owner's hand.

Sorcerer's Strongbox

{2}, {T}: Flip a coin. If you win the flip, sacrifice this artifact and draw three cards.

Six-Sided Die

Choose target creature. Roll a six-sided die.
1 — It has base toughness 1 until end of turn.
2 — Put two -1/-1 counters on it.
3 — Six-Sided Die deals 3 damage to it and you gain 3 life.
4 — It gets -4/-4 until end of turn.
5 — Destroy it.
6 — Exile it.

Mountain

Pippa, Duchess of Dice

{2}{G}, {T}: Roll a six-sided die. It becomes a green Die creature token with power and toughness each equal to its result.
{2}{U}, {T}: Reroll any die. (Activate only any time it makes sense.)

Inhumaniac

At the beginning of your upkeep, roll a six-sided die. On a 3 or 4, put a +1/+1 counter on this creature. On a 5 or higher, put two +1/+1 counters on it. On a 1, remove all +1/+1 counters from this creature.

Gruul Turf

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {R}{G}.

Jumbo Imp

Flying
As this creature enters, roll a six-sided die. This creature enters with a number of +1/+1 counters on it equal to the result.
At the beginning of your upkeep, roll a six-sided die and put a number of +1/+1 counters on this creature equal to the result.
At the beginning of your end step, roll a six-sided die and remove a number of +1/+1 counters from this creature equal to the result.

Forest

Sylvan Shepherd

Vigilance
Whenever this creature attacks, roll a d20.
1—9 | You gain 1 life.
10—19 | You gain 2 life.
20 | You gain 5 life.

Krark, the Thumbless

Whenever you cast an instant or sorcery spell, flip a coin. If you lose the flip, return that spell to its owner's hand. If you win the flip, copy that spell, and you may choose new targets for the copy.
Partner (You can have two commanders if both have partner.)

Hoarding Ogre

Whenever this creature attacks, roll a d20.
1—9 | Create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")
10—19 | Create two Treasure tokens.
20 | Create three Treasure tokens.

Swamp

Barbarian Class

(Gain the next level as a sorcery to add its ability.)
If you would roll one or more dice, instead roll that many dice plus one and ignore the lowest roll.
{1}{R}: Level 2
Whenever you roll one or more dice, target creature you control gets +2/+0 and gains menace until end of turn.
{2}{R}: Level 3
Creatures you control have haste.

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.

Mana Screw

{1}: Flip a coin. If you win the flip, add {C}{C}. Activate only as an instant.

Wyll, Blade of Frontiers

If you would roll one or more dice, instead roll that many dice plus one and ignore the lowest roll.
Whenever you roll one or more dice, put a +1/+1 counter on Wyll.
Choose a Background (You can have a Background as a second commander.)

Squirrel-Powered Scheme

Increase the result of each die you roll by 2.

Tavern Scoundrel

Whenever you win a coin flip, create two Treasure tokens. (They're artifacts with "{T}, Sacrifice this token: Add one mana of any color.")
{1}, {T}, Sacrifice another permanent: Flip a coin.

Steel Squirrel

Whenever you roll a 5 or higher on a die, this creature gets +X/+X until end of turn, where X is the result.
{6}: Roll a six-sided die.

Growth Spurt

Roll a six-sided die. Target creature gets +X/+X until end of turn, where X is the result.

As Luck Would Have It

Hexproof
Whenever you roll a die, put a number of luck counters on this enchantment equal to the result. Then if there are 100 or more luck counters on this enchantment, you win the game. (Count both rolls if you reroll a die.)

Rakdos Carnarium

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {B}{R}.

Golgari Rot Farm

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {B}{G}.

Myrkul's Edict

Roll a d20.
1—9 | Choose an opponent. That player sacrifices a creature of their choice.
10—19 | Each opponent sacrifices a creature of their choice.
20 | Each opponent sacrifices a creature with the greatest power among creatures that player controls.

Lobe Lobber

Equipped creature has "{T}: This creature deals 1 damage to target player or planeswalker. Roll a six-sided die. On a 5 or higher, untap it."
Equip {2}