how do plane cards work mtg Planechase works in Commander What is Planechase in Magic:

My guess is that Wizards looked too good in playtestingimpressive considering how Goblins and Zombies were allowed to thrive with significant power

The real power is that whenever you gain life, you get to put a +1/+1 counter on each Creature you control

(2023-10-13) The mana value of a split card is determined by the combined mana cost of its two halves

Mirror Entity

You might also want to be careful that you sequence things correctly in order to avoid downsizing larger creatures such as Ghalta, Primal Hunger

That said, they are "non-cannon" characters, and their inclusion in a set doesn't mean they're actually on that plane in a lore or story sense