That definitely ensures the smallest possibility of any damage occurring upon removal, so makes sense
As aristocrats decks aim to gain value from sacrificing creatures, often including a litany of cards with death-based triggers, Teysa can double the effectiveness of each of these triggered abilities, providing absurd amounts of value from what are normally somewhat unimpressive actions
This can stop your opponent from doing many things, including recovering HP by Evolving their Active Pokemon, getting Abilities they need on the field, or Evolving to bypass Status Effects
Slagstorm deals 3 damage to each creature on the battlefield for only three mana (or it can deal the last 3 damage to your opponent in a pinch)
This means that if you lose against your AI opponent or fail to complete one of the missions you are trying to complete, you can always try again without worrying about your stamina