Warp-Aci are the favoured summon of most cubi, as such, they get them for free during their level

progression. Anyone else can still summon one, using the rules for Improved Familiar

Warp-Aci count as having an level adjustment of 8

A warp-aci has the same stats as a pseudodragon of its level. It's caster level is the same as of it's owner for spell effects.

It however can't use poison - instead, it has at-will polymorph self, dimensional door and teleport

it has a +8 permanent bonus to Hide checks