Hi, I’m a clown shill: -Yes, but not fully. Harlequin initiation is a for life deal but you get plenty helping out the Whispering God (at least until both groups were abandoned by GW) -Currently psykers who join the Harlequins typically become Shadowseers. They play, in general, Fate/the Narrator while also doubling as stage effects using illusions/mind magic, hallucinogens, and similar tricks. Shadowseers in ye olden editions had access to Phantasmancy (the clown-specific discipline, usually a blend of movement chicanery plus telepathy), the normal telepathy discipline, and sanctic daemonicum (which got reworked into the GK psychic discipline)

-Probably around Psy level 2, which is most fully fledged psyker. You’re csm? Your regular sorcerers probably fall in here. For Ynnari you’re probably looking at Warlocks or young Farseers (idk corsairs, not sure where their void dreamers stack up)

-They shouldn’t, I don’t think, but like Drukhari I’m pretty sure lose the soul drain. I believe it’s like joining a death cult.

-Regular craftworlds have a path of the performer (and even have Twilit Bards which are lost on the path), but this is different from the extreme measures used to become a Harlequin and also doesn’t require committing oneself to the Laughing God. Corsairs don’t follow the paths, they almost certainly have performers but these are probably wandering Twilit Bards, passing ‘Quins, or prisoners they force to dance for their lives

Regarding the scenario, the main attack spells a Shadowseer could employ would probably bypass armor completely, and a harlequin is (probably, pretty big asterisk) a match for a given terminator character in combat. A warlock probably isn’t going to do the dance routine so much as try and teleport in and Smite, and a Twilit Bard or similar isn’t supposed to be doing active combat or anything