Light the Blue Touch Paper and Run Like Hell

"So, in summary, you are sending me to wage a prank war on history and myth's so-called greatest heroes and a sextet of upstart magic users, all for a dubious prize. I'm in." Given a second chance by Zelretch after falling from the Bifrost, Loki, partnered with a beautiful Caster, will wreak havoc on the Fourth Grail War...and perhaps find salvation...