adding debuffs?

[tinkthank]

The multitude of neat spells, especially of the support kind, is very nice in this game. I like that. Especially those of the buff types.
I sort of miss debuff spells however. The only ones I know of are those affecting protection.
Is there a particular reason why there are no spells which
- lower magic resistance of 1 target / square / whole battlefield?
- lower speed of 1 target / square / whole battlefield?
- lower attack skill of 1 target / square / whole battlefield?
- (probably imbalanced but: lower magic ability of 1 target / square / whole battlefield?)
and spells of similar types?
Would it make countering too easy?
Just curious
thanks much