Thanks for the info on promoting. As for the summoning focus … you’re clearly an optimist–you see one troop you want and think it’s worth trying for (which was obviously true for kenn). I’m a pessimist–I see two staff users out of the six focus heroes and think I’d absolutely end up with one of them if I got any 5* heroes at all.
EDIT (not a new post–want to make sure everyone’s voices are heard 
): I couldn’t help myself with a bunch of orbs burning a hole in my pocket, so to speak, so I tried my luck at summoning. The good news? No lousy healers. The bad news? Five 3* heroes. At least I got a 3* Olivia, thus making it unnecessary to promote my 2* version.