Missions in Dungeons

So, I was in Crystal Ruins for some missions. On the floor of the mission, Regice also happened to spawn. I couldn’t see Regice, and the mission tile was right in my eye sight, I go to complete the mission and Regice had started attack me and nearly killed me during the completion message!

Suggestion:
Give the player invincibility when a mission is completed, just like recruiting or learning a new move.

Why?
As my story shows, if you’re doing missions in higher level dungeons and that message stops you from protecting yourself, you’ve pretty much died.