Issei's first encounter with Dohnaseek ended with Issei using a bag of flour and a fireball to set off a dust explosion and light his opponent on fire.
The rescue of Asia and the ensuing fight with Raynare. Thanks to an altered chain of events, Issei followed Asia into the church after their first meeting where he sees Asia healing Dohnaseek and trying to heal Raynare (whose injuries were caused by holy damage and aren't regenerating normally). Raynare gets frustrated enough to jump straight into the extraction process and is about to lay hands on Asia when Issei literally kicks the door down. Said door splits in half under the force of the blow and the top half nails Raynare in the face and sends her flipping across the room.