"Testing The Domain Masters" 

Domain masters were sensitive to anything related to domains, so their bodies would also enter domains quicker and easier than ordinary ability users who weren't domain masters. 

Of course, normal ability users would also be dragged into a domain if they were enveloped by the domain, but domain masters, who could avoid domains as long as the domains weren't around, would be as helpless as ordinary ability users if a domain enveloped them before they could summon their own domains. 

No domain masters would like to enter another domain master's domain. Usually, domain masters only clash their domains, making the domains fight each other, overwhelming each other. 

The domain masters themselves would be inside their own domain, trying to 'eat away' their opponent's domain.