Although this ability only triggers when Mirri attacks, you'll undoubtedly be beefing her up with equipment, and first strike will deter opponents from blocking her
The Incredibles as a whole really come out as some of the most valuable cards in the set, and Syndrome rounds out the Incredibles Enchanted cards, with Syndrome being the most expensive of the bunch
Also, there are lots of X spells that create creatures at instant speed, like Call the Coppercoats, Decree of Justice, White Sun's Zenith, so you could set up an easy win in EDH by casting a big spell, attacking the next turn, and untapping to win
Kumena is a three-mana Green and Blue 2/4 with three abilities
In terms of upwards potential, you could easily get this deck into Bracket Three without even needing to include any Game Changers
It also introduces Junk tokens, which can be sacrificed to draw cards