Awful spell-monster combos

[Tvtyrant]

For awful combinations of monsters with spells. My entry is the Grell Druid casting Venomfire and doing +210 damage a round at CR 10.

[Deophaun]

For awful combinations of monsters with spells. My entry is the Grell Druid casting Venomfire and doing +210 damage a round at CR 10.
Depends: Is the grell targeting one person (10d6, average 35 damage from venomfire) or 10 people (average 350 damage from venomfire if they all hit)?

[Tvtyrant]

Depends: Is the grell targeting one person (10d6, average 35 damage from venomfire) or 10 people (average 350 damage from venomfire if they all hit)?

It should be 10 tentacles, each one doing an extra 6d6 damage from Venomfire on each. 60d6 overall.

[Deophaun]

It should be 10 tentacles, each one doing an extra 6d6 damage from Venomfire on each. 60d6 overall.
That's not how the grell's poison works. Updated in LoM, each tentacle hit beyond the first just ups the poison DC instead of delivering an additional dose.

Edit: And technically, it's never called a poison, just paralysis. It might not even work with venomfire to that extent.

[rot42]

Drowned (MMIII p 46; CR 8) + Solid Fog - everything within 30' starts drowning, cannot run away, and cannot see to target the teleports that require it.

[Runestar]

Any monster with an insane grapple mod and an AMF spell (somehow, such as a master specialist's 10th lv ability).