You always want to be creature-heavy, so make some tough decisions about whether to use your other slots on removal, Equipment or tricks theres a lot of options
Creature spells you cast cost less to cast for each creature you control with a +1/+1 counter on it
It doesn't copy whether that permanent is tapped or untapped, whether that permanent has any counters on it or any Auras and/or Equipment attached to it, and it doesn't copy any non-copy effects that have changed that permanent's power, toughness, types, color, abilities, or so on
if I was ranking these for Constructed or Cube instead of Commander, itd likely take the top slot
MDFCs have long been a deck-building hack as long as you are willing to use them as lands when needed
Her battle-specific big spell casting would go on to make a splash in the format in the form of Narset, Enlightened Master and Cecily, Haunted Mage