The Battle Nizer (バトルナイザー, Batoru Naizā) is a device used by Reionyx's, such as Rei and Kate, that allows its wielder to summon a monster through a system called MonsLoad (モンスロード Monsurōdo?). A Reionyx commands the monster, even when the monster gets injured too much, so that the Reionyx has no choice but to call him back. However, the Battle Nizer has a side effect of hurting the Reionyx as well.