Slot 12 Rare/Mythic Rare Slot Now we venture into the Big Finish Chapter
Activated mana abilities may be played both when a player has priority and in process of casting a spell, activating an ability, resolving a spell or ability, if any such action requires a mana payment
It's also a clear reference to Master Splinter from TMNT , so that instantly makes it better
Alongside cards including Laboratory Maniac, Thassa's Oracle, and Angel's Grace, Ad Nauseam makes for an alternative win condition that will end a game of Commander on the spot
The Convoke ability makes it sometimes free, which increases the odds that you'll be able to play this, plus your own boardwipe, in the same turn
Mount Velus Manticore gets a special shout-out for its slightly more subtle synergy with artifact creatures