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.

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

ocT: Add {U} to your mana pool. Cephalid Coliseum deals 1 damage to you.
Threshold {U}, ocT, 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.)

Tarkir: Dragonstorm Commander

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

Modern Horizons 3

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.