Hmm, is there a bug with the "+5 damage for one level" boon? It feels like in some cases it then does -5 damage for each level after that instead of just the next one.
For instance, I just had the following sequence:
+5 dmg for one level (now damage 6 for that level)
+3 dmg (now damage 4, normal since it reset after the previous level)
+1 dmg (now damage 2 instead of 5???)
Something weird like that happened in another game too though I don't remember the exact sequence of power-ups.