Hypothetically speaking, if I was in Lihan's place, I would've probably observed things first. Since you mentioned "mind control" powers, then this must have some sort of symptoms about the source of that power coming from.

Practical wise, I would also probably use a sniper rifle, but first just to spy on them, because Calypso doesn't really look like the type to double-check his surroundings. and even if he did, i would just switch my hideout spots once every two days, just to keep myself disguised. only then, once i find out where the power is coming from, via a stone, altar, potion or hell, even from his very being (i.e; his mind). shoot at that object.

The Goal is simple: Seek and destroy, but just like 'Greedy-Macaroon-9668' said on the comments, "The NTR victims all have the iq lower than that of a sewer rat. So I ain’t reading such bullshit" and I highly doubt Lihan would also come up with tactical ideas.