surtr ivs

That's about as bad an IV as you can possibly get, and yet he still has 48 def on enemy phase, which means he's completely usable. But I probably wouldn't inherit anything onto him I didn't intend to give up. I'd say probably every single other possible IV is better than this one, so if you intend ever to get him again (including on this banner, because you're getting a good price), say, for fodder, this IV is probably getting sac'd.

Of course, even if you intend him for fodder, you can use the base kit as long as you please. Zero investment needed.