[Meglobob]

Yea, HoneyBadger has got it spot on. Most summons are not worth it because you are getting 1 or 2 units/per turn and missing out on RP's.

Its nearly always better to save your gems/blood slaves and research a higher level summon spell.

Sombre has gone through a load of summon spells and suggested generally increasing there numbers you get per casting.