Any abilities that triggered during this process are then put on the stack, starting by those controlled by the active player in an order of that player's choice, then continuing with each other player's abilities in turn order
Deeproot Elite's effect is fairly elegant and clean: when a Merfolk enters, you get to put a +1/+1 counter on another Merfolk you control
So Shimmer works with two separate styles of player
Kaya, Spirits Justice Kaya, Spirits' Justice can drop, exile your Cityscape Leveler from your graveyard (while also surveilling 2) and turn a Clue or Food token, not just a thopter or spirit into a copy of it that flies
Then theres desirability among the casual playing group is it unique, splashy and fun
Thats no complaint, of course, but rather a fundamental aspect of Magic and how we as players experience that art