orion

Euryale + Euryale + Mata Hari/Stheno can also do the job. He's pretty much died while his boner still standing.

Euryale have Charm, can steal Gawain NP gauge, faster NP gain, also technically same NP damage with Orion.
2x Charm, 1x NP Drain, fast NP gain, Art Cards UP and massive damage vs male. Bring her along with Orion for max result.
Euryale + Mata Hari + Orion, Euryale + Orion + Stheno, Euryale + Euryale + Orion. So much good team comps out there.

Euryale NP 5 = Orion NP 1, not too much difference.

Bonus : Euryale/Orion ( Black Grail/Heaven's Feel/Art of Death ) + friends Waver + Mozart + Caesar = Gawain very easy mode.
MLB Heaven's Feel/Black Grail/Art of Death for memes.

You borrow your friends Orion, you can't borrow Waver or Merlin, but if you use your own Euryale you can borrow your friends Waver.

See the difference ?

I won with this line up with a level 70 euryale NP5 as support. 2 command seals were used for back to back NP + charm. Stun from combat uniform.
Another charm from Marie.
Drain from tamamo and euryale. Remember to use arts cards buffs on euryale. Bumps her damage up to 100k to 150k per NP.