Since none of the modes have targets, you don't have to choose which creature is getting the counters or which cards you're returning until Gix's Command resolves
Lets look at an example from our store
Then each creature that isn't an Insect, Rat, Spider, or Squirrel gets -1/-1 until end of turn for each creature you control that's an Insect, Rat, Spider, or Squirrel
0-cost cards One thing that wont be included in the list are 0-cost cards, like Black Lotus, Lotus Petal, or Ornithopter
(It loses its other colors and creature types.) If a player is instructed to put a card into their graveyard from their library without using the word "mill," (by the effect of Rowan's Grim Search from Wilds of Eldraine , for example), that card isn't a legal target for The Master's last ability