DIMINISHING RETURNS

Some spell help files will denote that they have diminishing returns. When these spells are cast on a target, and the target makes a save, the caster gets a -5 to spell DC for subsequent casts (of the same spell) on that same target for 5 rounds (about 30 seconds). Each subsequent cast resulting in the target making a save will reset the timer.

The diminishing returns are unique to the target and caster.

Teleport spells have their own type of diminishing return. When a teleport fails, specifically, against a teleport ward, the caster has diminished potency against that ward for the next 30 minutes.

Scry spells, inherently, have diminishing returns when failing a scry check against the target's scry ward. The same rules apply here as with teleport spells.

These listed types of spells, in the past, have made things like teleport wards and scry wards worthless because of the ability of the teleporter or scryer to continuously cast to overcome them. This is meant to keep spam casting of certain spells to a minimum.