Not bad.
You use a lot of colors, much of which can be reduced.
Ifrit: Could use a bit of that luminescence. I mean, c'mon, Fire Summon? He should be glowing.
Besides that, very nicely drawn, but there are a few black lines here and there I'd lighten up, like his wrist-shackle thingy.
That other summon: Only thing I got against this is the color count. Some contrast may help as well there.