The question is about Hearthstone card. Each Hearthstone card has some funny description. "Lay on Hands" card described as "A grammatically awkward life saver". So the question is why it is grammaticaly awkward?
It's a stripped version of the 'healing' method "The laying on of hands" which, whether effective or not, describes the act more clearly. You put your hands on someone as a method of healing.
That gives us the "life saver" part of the pun.
Stripped to "lay on hands" makes it sound more like you are laying down with your hands underneath you; or that someone just commanded you to do that, as it is structured more like an instruction than a description of what you are currently doing.
It doesn't adequately describe whose hands or what or who would be doing the laying.
It requires knowledge of the original full structure to really make sense.