With the Cultist Sorc already getting a Lesser Planar Binding token at level 8, albeit one that doesn't allow multiple summons, them also getting Lesser Planar binding at 10 creates Redundancy.
I'd say give them Summon V at 10 since almost every Cultist Sorc would already take it anyway. This means their other level 10 spell is actually a choice instead of pretty much everyone ending up with Summon V and Lesser Planar Binding.
I'd say give them Summon V at 10 since almost every Cultist Sorc would already take it anyway. This means their other level 10 spell is actually a choice instead of pretty much everyone ending up with Summon V and Lesser Planar Binding.