Broken combo or bad reading? (suffocation)

[Anwyl]

Lv15 Witch
Hexes: Cackle, Misfortune
Feats: Spell Perfection, Extend Spell, Persistent spell, Heighten spell
Spells: Suffocation

Witch actions
Round 1: Misfortune (standard action), Cackle (move action)
Round 2: Extended Persistent Heightened Suffocation (standard action), Cackle (move action)
Round 3-27: Chase enemy down (move action), Cackle (move action)

Assume the enemy fails the save for misfortune.
Suffocation grants a fort save to end the spell with a minor penalty. Misfortune makes you roll 2 dice and take the lowest. If the lowest die passes, you've succeeded at a save, so Persistent spell says you must make another save. Misfortune says you roll 2 dice and take the lowest. So you have to roll 4 dice, and have them ALL pass in order to get out of it.

If you fail any of those, you have to make 1 save per round to avoid going to 0hp. Misfortune * persistent makes that 4 saves per round. Normally you'd only have to do that for 3 rounds, but extend pushes that to 6.

End result: 4 saves, fail any of them, make 24 saves or go to 0 hp.

This seems too good to be true for a lv 6 spell with lv 5 saves, or lv 7 spell with lv 6 saves via heighten. Am I misinterpreting something somewhere in there?

[Elamdri]

Misfortune + Persistent Spell is nasty business. Even better if you have another caster to back you up with the spell, then you can potentially get your combo off round 1.

[deuxhero]

Neat combo, but I think there are much nastier things you can do with 8th level spells alone, not to metnion all the feats you speant.

[Timothy Hanson]

Witch Actions

Round 1: Misfortune, Cackle
Round 2: Slumber

Any other Party Members Action:
Round 1: Move into Melee Range
Round 2: Coup de Grace

This can be done from level 2 or so on. Might work on a few less things though.

[Malignor]

Or, if they have a high Fort save but low reflex, here's what my Water Elemental Bloodline Sorcerer build has from level 14 onward:

Quickened Aqueous Orb (level 3+4, reflex) + Suffocate

Even if the target makes the Fort save against Suffocate, they are "gasping for breath" while underwater... so they drown.

High Fort is far more common than high Reflex, so I think this is a pretty nice one-two combo.

[Mahtobedis]

Round 1: quicken I'll omen, Icey Tomb