User blog comment:The Black Dragon of Orihara/Aetherium Tournament's Arrival; Spring '16 Sign-ups/@comment-5842470-20160308204851/@comment-26037781-20160308220552

(Pulled directly from the Rules section)

Each character is allowed to use up to two summons to help them in the 1v1 bracket, but not in the doubles, trio, or party brackets.