If he has several different healing powers, then he has more than four modes. The question is whether they should be a nested array or a normal one. I'm definitely of the opinion they should be a normal one. If anyone on the dev team has ever suggested nested arrays should exist, I think they are clearly wrong. Powers used simultaneously should be an array slot, ones used at different times should be separate slots. Allowing nested arrays is basically nearly infinite points. There is no level at which I would consider it sensible, fair, and not a crock.