Each player chooses a number of lands they control equal to the number of lands controlled by the player who controls the fewest, then sacrifices the rest. Players discard cards and sacrifice creatures the same way.

Choose odd or even. Destroy each creature with mana value of the chosen quality. Then gain control of all creatures until end of turn. Untap them. They gain haste until end of turn. (Zero is even.)

Prevent all combat damage that would be dealt this turn.

Double strike
Éomer enters with a +1/+1 counter on it for each other Human you control.
When Éomer enters, target player becomes the monarch. Éomer deals damage equal to its power to any target.

When this creature enters, search your library for an Aura card that could enchant it. If this creature is still on the battlefield, put that Aura card onto the battlefield attached to it. Otherwise, reveal the Aura card and put it into your hand. Then shuffle.

Whenever this creature is dealt damage, it deals that much damage to you.

Lightning Surge deals 4 damage to any target.
Threshold — If there are seven or more cards in your graveyard, instead Lightning Surge deals 6 damage to that permanent or player and the damage can't be prevented.
Flashback (You may cast this card from your graveyard for its flashback cost. Then exile it.)

, : Creatures of the creature type of your choice attack this turn if able.

This spell can't be countered.
Counter target noncreature spell.

Flying
Whenever Ganax or another Dragon you control enters, create a Treasure token. (It's an artifact with ", Sacrifice this token: Add one mana of any color.")
Choose a Background (You can have a Background as a second commander.)

Blue creatures you control can't be blocked.

Exile target creature you control, then return that card to the battlefield under your control.

Landfall — Whenever a land you control enters, you may mill two cards.
, Sacrifice this enchantment: Create X 1/1 green Minion creature tokens named Moloid, where X is the number of permanent cards in your graveyard. The tokens have "Whenever this token attacks, you may mill a card." Activate only as a sorcery.

At the beginning of your upkeep, for each land target player controls in excess of the number you control, choose a land that player controls, then the chosen permanents phase out. Repeat this process for artifacts and creatures. (While they're phased out, they're treated as though they don't exist. They phase in before that player untaps during their next untap step.)

Destroy target green or white creature.

Extort (Whenever you cast a spell, you may pay . If you do, each opponent loses 1 life and you gain that much life.)
Artifacts and creatures your opponents control enter tapped.

Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.)
: Add , , or .

, : Target player mills two cards.

Target creature gets -1/-1 until end of turn for each Swamp you control.

Draw four cards, then choose X cards in your hand and discard the rest.