Is anigrow

Caster level: druid 5, ranger 4, sorcerer / wizard 5
Innate level: 4
School: transmutation
Descriptors: none
Component(s): V, S
Range: medium
Immunity type: none
Saving throw: fortitude negates
Spell resistance: yes
Area of effect/target: up to one animal/2 levels, within a 15 ft radius spread
Duration: 1 turn/level

Description: This alteration changes each animal's size category to the next larger, grants it a +8 size bonus to strength and a +4 size bonus to constitution (and thus an extra 2 hit points per hit die), and imposes a −2 size penalty to dexterity. The creature's existing natural armor bonus increases by 2. The size change also affects the animal's size modifiers to armor class and attack rolls, and affects its base damage.

Custom spell: This spell is part of the Grimoire and is not part of standard Neverwinter Nights.