When I summon the royal adviser she only lasts until she gets hit. She has over 43000 hp or whatever you call it and should last a long time. I can only use her if I stay behind my units.
I just click her once to summon her, then use her 3 spells and either wait for the timers so i can use her spells for the 2nd time or click her icon to switch back. I originally made the mistake of double clicking her like the other guardians which sends her back.