You swap a creature summoned by a conjuration (summoning) spell for a creature you could summon with a _summon monster_ or _summon nature’s ally_ spell. The new creature must be an option from a spell of the same level or lower as the spell that summoned the target. The new creature cannot be summoned into an environment that cannot support it. The target can attempt a Will saving throw to negate this effect, but if the target is under your control, it receives no saving throw. _Alter summoned monster_ does not alter the duration of the spell that summoned the target, nor does it affect any additional creatures summoned by the same spell as the target. The new creature has the same conditions and amount of damage as the target creature, and remains affected by all curses, diseases, poisons, and penalties that affected the target, but no other spells or effects carry over. _Alter summoned monster_ is a spell of the same alignment type or types as the creature for which you exchange the target. An eidolon can’t be targeted by this spell.