The Axolotl Nurse Game Over is an ending which occurs if the Cutie Knights lose to the Dragon Schoolgirl during the Hunting for Clues event.
Contrary to most game overs resulting from losing fights, what happens here was entirely accidental. After losing the fight, most of the Cutie Knights are immediately teleported away, leaving only Eric(a). Their opponent, the unnamed Dragon Schoolgirl, actually tries to help Eric(a) up at this point so that she can lecture her. Unfortunately she misjudges her strength, accidentally tossing Eric(a) into the mutagenic slime. Eric(a) almost immediately ends up going under before the schoolgirl is able to pull her back out, much to her chagrin.
Some unspecified amount of time later Eric(a) comes back up to the surface in terrible shape, luckily happened upon by a couple of the forest denizens. The dryad stays to try and stabilize the grievously injured Eric(a) while the elf goes to retrieve their boss, Nylisa. By the time Nylisa arrives, Eric(a) had miraculously begun to heal on her own, still in bad shape but notably less severe. Eventually they manage to nurse Eric(a) back to health, but her time in the mutagenic slime has evidently both changed her in form, and badly damaged her memories.
As the new Eric(a) would find, not only does her new body heal quickly, but she has quite knack for healing magic as well. She quickly develops a reputation as the most skilled healer in the forest, and somehow acquires a sexy nurse uniform. Eventually her friends even manage to track Eric(a) down, happy to find her if shocked at her transformation. Unfortunately even then her memories do not return.
The new axolotl girl Eric(a) does end up returning to the camp, but is unable to continue being a Magical Girl as she has lost all aptitude for offensive magic. With her newly found gift for healing magic, Eric(a) instead takes up a role as Olivia's assistant.