Because Altered Ego is not a double-faced card, it won't be able to transform
Some commanders aim to smash the opponent in combat, such as Omnath, Locus of Rage, or they are "voltron" builds, such as Dragonlord Ojutai or the famed Uril, the Miststalker
Heres a little more clarity on how it works: Split cards function as two distinct cards, and the spell you cast only has the characteristics of the half you are casting
Cruella De Vil has a resource cost of 2, attack power of 1 and a defense rating of 3
However, there are better alternatives like Natural Affinity or Kamahl, Fist of Krosa, which offer similar effects with additional benefits, making Living Plane less optimal for competitive play but still a fun and unique choice for casual or themed decks