Karla Fodder

Outch thats hard. Well Wrath is also available on Nephenee but Odd Speed Wave is only available to her. Besides that you should look at your favourite character and build according to that.

If you do plan to fodder off Karla use her for Wrath because many units have amazing builds with wrath. While in the other hand Even Spd Wave is useful it kinda situational and a few unit can benefit from like bladetomes.

You should cap her merit and then use her as wrath fodder because wave skills are, for the most part, garbage outside of very specific circumstances.

I was unlucky enogh to pull a -atk +res karla but I invested quite a bit and she still does the job that she is meant to do, honestly the ivs could be worse by being a -spd

Is it because you're waiting for a good IV to build? She will still rip a lot of stuff to bits despite the atk bane.