Khatvanga is a very poor nuking staff compared to other options. I'd bet Mpaca's Staff out-nukes it and has refresh+2 on top as well.
Use club/shield and moonlight. Need more mp, switch to staff and AF coat, cast one impact in an OA set -> Myrkr -> back to club/shield.
AF coat won't ever give you back more MP than the cost of the spell. It cannot be used to entirely refill MP.
Most gearswaps have a setup for auto-using AF coat when MP is under some threshold, usually 40-30%. The same setup can be used to auto-swap to staff on that same threshold if you want.
Then it's just nuke as normal, when you see yourself in a staff wait for TP and use Myrkr to get back to full MP.
You need to nuke to get TP to Myrkr. Which is where impact comes in, one cast and you have >1k TP with a good OA set.
How is nuking for ***dmg with one staff so you can get slightly more MP on Myrkr better than nuking for more dmg while waiting for slightly more TP with another staff.
Idk how much MP a 500 TP bonus works out to.
You don't need OA sets for staff nukes, just nuke normally if you're not doing impact. As long as the dmg is comparable to club, it won't hurt you much.
Nothing says efficiency like changing weapons every 6 nukes to get your MP back, thus dropping all of the TP you gained from those 6 nukes.
If someone asks you what kind of condoms they should use to swallow razorblades, you shouldn't give them a recommendation, you should tell them not to swallow *** razorblades.
Use a GD staff, lock it, and then use Myrkr (with a proper set) when your MP gets low.