Flying
When Moseo enters, create a 1/1 black and green Pest creature token with "Whenever this token attacks, you gain 1 life."
Infusion — At the beginning of your end step, if you gained life this turn, return up to one target creature card with mana value X or less from your graveyard to the battlefield, where X is the amount of life you gained this turn.
If a card in a graveyard has {X} in its mana cost, X is 0 for the purpose of determining its mana value.
20 Mar 2026
Moseo's last ability will check as your end step starts to see if you gained life this turn. If you didn't, the ability won't trigger at all. It's not possible to gain life during your end step in time to have the ability trigger.