A player with a Ice-themed witch wants permission to take the Winter Oracle's Freezing Spells Revelation as a hex (or possibly a feat). I don't see a problem with this, since feats, Revelations and Hexes are about equivalent in power.
I'm thinking about giving it the standard "once per enemy" drawback of most offensive hexes for consistency, but am open to other kinds of limitation, such as a feat or level prerequisite, action usage, or only allowing it to affect one target per spell. (Elemental Focus or Chilling Amplification look like good candidates for a feat prereq, though I'm not really sure how the latter would stack)
What do people think? Should the player be allowed to take it as it is written for oracles or should I tweak it first?
You linked the revelation to the feat Chilling Amplification.
The Revelation is here.
Whenever a creature fails a saving throw and takes cold damage from one of your spells, it is slowed (as the slow spell) for 1 round. Spells that do not allow saves do not slow creatures. At 11th level, the slow duration increases to 1d4 rounds.
The Extra Revelation feat can gain this if you have the right characteristics. Allowing this character to gain the revelation via a feat slot if you want to is fine.
The revelation makes no sense as a hex, as hexes are usually actions to affect something, while the revelation merely alters some spells you cast.
No need for adding a drawback, since it already costs a precious feat slot.
To make it work as a hex, I would say it would be at will, but the target must be suffering ongoing cold damage of some form. Repeated application only adds to the duration with overlap. The action economy is using one of your standards to make them staggered a round [1d4r later] is fairly balanced, in my opinion.
/cevah