Enchant creature you control
When Setessan Training enters the battlefield, draw a card.
Enchanted creature gets +1/+0 and has trample. (It can deal excess combat damage to the player or planeswalker it's attacking.)
If the creature Setessan Training would enchant is an illegal target by the time the Aura spell resolves, the entire spell doesn't resolve. It won't enter the battlefield, so its ability won't trigger.