Modern Horizons 3

Cephalid Coliseum

{T}: Add {U}. Cephalid Coliseum deals 1 damage to you.
Threshold — {U}, {T}, Sacrifice Cephalid Coliseum: Target player draws three cards, then discards three cards. Activate only if seven or more cards are in your graveyard.

From the Vault: Realms

{T}: Add {U} to your mana pool. Cephalid Coliseum deals 1 damage to you.
Threshold — {U}, {T}, Sacrifice Cephalid Coliseum: Target player draws three cards, then discards three cards. Activate this ability only if seven or more cards are in your graveyard.

World Championship Decks 2002

Odyssey

oc
T: Add o
U to your mana pool. Cephalid Coliseum deals 1 damage to you.
Threshold o
U, oc
T, Sacrifice Cephalid Coliseum: Target player draws three cards, then discards three cards from his or her hand. (Play this ability only if seven or more cards are in your graveyard.)