Isn't the shorten turn item a flat -5 turns or something like that?

Hades/Eligor/Nebiros would be in the 10th event/gacha update after Typhon. That's about 3 and a half months away?
Nyarlathotep (SR; in same update as Cthulhu and Dagon, who are water) would be in the 14th event/gacha update after Typhon. That's another month and a week after Hades/Eligor/Nebiros.

Osiris would be the dark healer; she's an SSR. And she'd be about.... a little over 6 months away.