I dont see how you're struggling with imps Choco, what you're doing is almost exactly the same as what I do. Only difference is I dont open with Sprout Smack, nor do I even bother to equip it. Heres my spell set see if it helps:
Battle Dance, Head Butt, Uppercut, Frenetic Rip, Disseverment, Vertical Cleave, Firespit, Chaotic Eye, Refueling, Metallic Body, Cocoon, Plasma Charge, Magic Fruit, Actinic Burst, Bludgeon. I tend to fully buff first, shadows, Metallic Body, Cocoon, Refueling, and when I run in I tend to open up with Head Butt since most imps like to start with an aga, sleep, or some other spell, then go in with Disseverment first, followed up by another Head Butt, get a few melee swings in, Head Butt again, then end it with Frenetic Rip (and if necessary, Bludgeon). After the first imp its a cake walk since I tend to have TP availalbe to opend up with Chain Affinity: Savage Blade > Disseverment = Distortion (which tends to knock the imp down to 50%ish).