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It is almost inevitable that SOME of the combinations I was hoping for are not possible (as a /kin with a buffable nuke and a group sleep/hold would be horrifically overpowered - of course, you CAN get them on the hero side...)
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Group sleep - don't they just wake and pummel you with an AOE? At least the group immob keeps them in the damage zone

or maybe I'm missing something
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Black Scorpion
- AoE immob with -fly and -jump. Useful for PvP I would imagine.
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IMHO the single target holds (stacked where possible) would be a better bet for PvP.
But you're right, the holy grail of an AOE hold plus buffable AoE would be rather tasty