They are restricted in lower-power, casual brackets (0 allowed) and limited in mid-power brackets
If some of the targets become illegal for Mythos of Vadrok, the original division of damage still applies, but the damage that would have been dealt to illegal targets isn't dealt at all
Kaladesh Inventions has a cycle of five mythic rare cards that appear in the Kaladesh set
Additionally, since the Pokemon in the illustration are babies and Igglybuff is incredibly cute, the card also represents innocence
This is the kind of common that felt like it lurked in every single Khans pack, mocking you as you kept cracking to get that playset of Monastery Swiftspears
In Standard, this could theoretically work well alongside Cori-Steel Cutter, and cards like Sword of Wealth and Power