Red: Valakut Awakening, Unexpected Windfall, Seize the Spotlight, Thrill of Possibility, etc
Imprint was a mechanic from Mirrodin block (and later reprinted in Scars of Mirrodin block) where the player had to exile a card when casting the spell (the exiled card came from different places), which then was used as a marker to determine something about the spell
At the same time, opponents receive 2 poison counters from Marsh Viper every time it damages them even though its power is only 1
This allows commanders like Child of Alara or other death triggers to actually function as intended while maintaining the command zone
Cranial Plating could also be mentioned here, but thats only good in one deck
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