Morph Blender (3.5e Feat)
From D&D Wiki
 Morph Blender [Special]
Now you see him, now you... where are you?
Prerequisite: must be able to change shape in one of the following five ways: change shape supernatural ability, shapechanger subtype, polymorph as a spell-like ability, able to cast the polymorph spell, wild shape or similar class feature
Benefit: You can hide in any sort of terrain, even without cover or concealment. You also gain a +2 bonus on Hide checks. If you already have the ability to hide without cover or concealment (see ranger), you instead get an additional +4 bonus on Hide checks.
Normal: you need cover or concealment to hide.
Special: This feat can be taken up to 3 times. If you cast the polymorph spell, has polymorph as a spell-like ability usable less often than at will, or has the wild shape class feature, then this feat loses function when you cannot use them.