Dragonbroods' Relic (140) [Tarkir: Dragonstorm]

{T}, Tap an untapped creature you control: Add one mana of any color. {3}{W}{U}{B}{R}{G}, Sacrifice this artifact: Create a 4/4 Dragon creature token named Reliquary Dragon that's all colors. It has flying, lifelink, and "When this token enters, it deals 3 damage to any target." Activate only as a sorcery.