Eidolon of the Great Revel (A25)

Enchantment Creature — Spirit

Whenever a player casts a spell with mana value 3 or less, Eidolon of the Great Revel deals 2 damage to that player.

2/2

Xenagos reveled while Theros burned.
Cyril Van Der Haegen
128/249
uuid: 46669750-20d3-58c4-b834-1afb6814f554

2018-03-16:
Casting Eidolon of the Great Revel doesn’t cause its own ability to trigger. It must be on the battlefield when the spell is cast for its ability to trigger.
2018-03-16:
The amount of mana spent to cast a spell doesn’t change its converted mana cost. For example, a card cast with its morph ability has a converted mana cost of 0 even though {3} was paid.
2018-03-16:
The converted mana cost of a spell with {X} in its mana cost includes the value chosen for X.