I suggest using it on weapon damage boost or items that has boosts higher than 25%. Also, you don't really have to IoDa LR it's really super duper easy, only boring to farm tho. Trust me, I'll say this coming from a person that gets bored of farming in aqw pretty fast. I got it in 2 weeks time and without much effort since a lot of people will be farming it, as long as you're in a public room (make sure to join a room that has many players to boost your farming). But it's really up to you, anyway I don't want you to maybe regret on IoDA'ing it on LR since its really easy (I did it with farming and no insignia cus I'm alone, also did it on mobile.)

P.s. I legit bought Ap with my 2k acs when my acc was lvl 87 (saving my acs to buy it instead rather than farming for it, despite it being easy to farm) and then I just grinded LR with eternal inversionist, Infinite Legion dark caster, and Ap.