Ori and the Blind Forest: Definitive Edition

The Bash ability is unlocked in the Ginso Tree. You can hold near enemies, projectiles, or hanging lights to shoot yourself in any direction by aiming the arrow in the direction YOU want to go, so to aim a projectile using Bash you want to aim yourself AWAY from whatever you're targeting. If you're Bashing off a pink fireball, for instance, and the enemy you want to kill is below you, you want to aim yourself up. There are plenty of opportunities for this, and since enemies respawn, you can do it on the same enemy until it unlocks if you'd like.