But that's hard to make work and easy to disrupt with removal of the Commander himself or by the Anthems (Glorious Anthem), Auras (Rancor) or Equipment (Bonesplitter), and if you sweep you really break him with mass removal, and recasting a five cost is rough
However, he falls into ruin after Kaiba markets and patents his invention first and seeks to destroy the Kaiba Corporation
Young Pyromancer is only 1 creature initially, but if you run lots of instants/sorceries, he will generate more and more tokens for no additional cost
As a result, Pegasus is able to make full use of Toon Worlds abilities without sacrificing any life points
Again, to be able to properly use a spell like Undercity Plague will require careful planning and proper board positioning, but its certainly a cipher card that can get out of control