Buffs that hurt, especially casters

[nargbop]

Yes, you read that right. Buffing effects that hurt you. I want to bury an enemy in irony.

The idea I'm working with is from the Warweaver Handbooks Black Tactica edition LINK, which shows a silly thing you can do with a Glyph Seal from Magic Item Compendium.
The original idea is, put Tenser's Transformation on the Glyph Seal, then tag the enemy caster with it.
I don't have Sanctum spell or other metamagic reduction cheese, so I am limited to 6th level spells or lower.
Fun spells so far :
Veil of Undeath, then turn him

[arguskos]

Burning Rage (PHB2). Get some combat benefits, but take fire damage constantly during it.

[Claudius Maximus]

Aquatic Escape.

[Mikeavelli]

I once had a lich cast brilliant aura on the party...

[dspeyer]

Rage -- Usually seen as a melee buff, but "identical with a barbarian’s rage", which means no spellcasting and no dex skills. As a bonus, it has no saving throw.

Enlarge Person -- Again, usually a melee buff, but darned inconvenient for anyone else.

Neither has the harmless descriptor.