Grunker
RPG Codex Ghost
Yea, the summons are amazing. Elementals stay forever, have the same level as the caster and twice the HP and the Fire Elemental at least can teleport around willy-nilly.If I went with more than 1 level rogue dip I would probably dip 3 levels into rogue so you get subclass + cleric 10th level feature is not important.
Cleric 6th level spell is not must have I pretty much only used this which is pretty great though
The Planar Ally spell is bound to be underrated. It's actually quite good. The three summons each have unique abilities and they stay with you permanently (until long rest).
The only reason you wouldn't cast it, really, is if you only have one slot and you use it for Feast.
Worst one is druid level 4 dryad summon. Two summons for the price of one, and the dryad hits laughably hard with her Shillelagh :D