I think Destiny Bond is an underrated move that can definitely increase the effectiveness of Gengar's spin blocking capabilities. If it switches in on Forretress' Gyro Ball (which is a 2HKO after Stealth Rock) it can simply Destiny Bond and take Forretress down with it, letting you keep your hazards up for the rest of the game. This also works against Tentacruel, you switch in on a rain-boosted Scald (2HKO), Destiny Bond, then permanent hazards. In conclusion, you may have trouble fitting Destiny Bond onto a Gengar set, but it increases Gengar's effectiveness as a spin blocker and eases prediction by allowing you to throw Gengar in front of almost any spinner (Starmie needs to die -_-) with the knowledge that regardless of whether they spin or attack, your hazards will still be up by the time they switch out / get KOed.
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