Priority Boarding

Whenever you roll a die, you may reveal the top card of your library. Do this only once each turn. Whenever you reveal a card with mana value less than the result this way, you may exile it. If you do, you may play it this turn.

Forge of Heroes

{T}: Add {C}.
{T}: Choose target commander that entered this turn. Put a +1/+1 counter on it if it's a creature and a loyalty counter on it if it's a planeswalker.

Swinging Ship

Visit — After the first combat phase this turn, there's an additional combat phase. At the beginning of that combat, untap all creatures that attacked this turn.

Grateful Apparition

Flying
Whenever Grateful Apparition deals combat damage to a player or planeswalker, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Captain Rex Nebula

At the beginning of combat on your turn, choose target nonland permanent you control. Until end of turn, it becomes a Vehicle artifact with base power and toughness each equal to its mana value, and it gains crew 2 and "Crash Land — Whenever this Vehicle deals damage, roll a six-sided die. If the result is equal to this Vehicle's mana value, sacrifice this Vehicle, then it deals that much damage to any target."

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.

Vexing Puzzlebox

Whenever you roll one or more dice, put a number of charge counters on Vexing Puzzlebox equal to the result.
{T}: Add one mana of any color. Roll a d20.
{T}, Remove 100 charge counters from Vexing Puzzlebox: Search your library for an artifact card, put that card onto the battlefield, then shuffle.

Ferris Wheel

Visit — Choose target creature that hasn't been phased out with Ferris Wheel. That creature phases out until you roll a 3 or less while rolling to visit your Attractions.

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

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, Blade of Frontiers.
Choose a Background (You can have a Background as a second commander.)

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Farewell

Choose one or more —
• Exile all artifacts.
• Exile all creatures.
• Exile all enchantments.
• Exile all graveyards.

Karn's Bastion

{T}: Add {C}.
{4}, {T}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Skullclamp

Equipped creature gets +1/-1.
Whenever equipped creature dies, draw two cards.
Equip {1}

The Chain Veil

At the beginning of your end step, if you didn't activate a loyalty ability of a planeswalker this turn, you lose 2 life.
{4}, {T}: For each planeswalker you control, you may activate one of its loyalty abilities once this turn as though none of its loyalty abilities have been activated this turn.

Plains

Boros Signet

Clown Car

When Clown Car enters, roll X six-sided dice. For each odd result, create a 1/1 white Clown Robot artifact creature token. For each even result, put a +1/+1 counter on Clown Car.
Crew 2

Command Tower

Brazen Dwarf

Whenever you roll one or more dice, Brazen Dwarf deals 1 damage to each opponent.

Complaints Clerk

When Complaints Clerk enters, open an Attraction. (Put the top card of your Attraction deck onto the battlefield.)
Whenever you roll a 1, create a 1/1 white Clown Robot artifact creature token.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Generous Gift

Destroy target permanent. Its controller creates a 3/3 green Elephant creature token.

Mountain

Repeated Reverberation

When you next cast an instant spell, cast a sorcery spell, or activate a loyalty ability this turn, copy that spell or ability twice. You may choose new targets for the copies.

Clown Extruder

Visit — Create a 1/1 white Clown Robot artifact creature token.

Comet, Stellar Pup

0: Roll a six-sided die.
1 or 2 — [+2], then create two 1/1 green Squirrel creature tokens. They gain haste until end of turn.
3 — [−1], then return a card with mana value 2 or less from your graveyard to your hand.
4 or 5 — Comet, Stellar Pup deals damage equal to the number of loyalty counters on him to a creature or player, then [−2].
6 — [+1], and you may activate Comet, Stellar Pup's loyalty ability two more times this turn.