Get a dedicated healer and if possible a tank to guard you as well in Mabinogi. Move in, towards enemy caster group and make sure you catch most of the healers otherwise it is a bad rift. Try to keep enemies there (that Tank friend can actually help a lot) and help the Sorcerers and Marauders AoE them to death. You will die a lot at first tries until your party learns how to do it but once you learn you will probably love it.
Could skip this last level(Mabinogi powerleveling) zone to be honest and talk about it in next tier, but for a Magus playing with friends (or a guild premade or something), it is actually worth it to spec for Chaotic Rift as soon as possible. At Rank 29 you can get (just) Chaotic Rift by going full Daemonology. Then you should add all the other useful things, including Agonizing, Aegis and Daemonic Pact as you continue leveling(mabinogi gold). The idea behind RvR with Chaotic Rift is the following. Focus on survivability stats (Wounds, Toughness, Initiative) and abilities (Misdirection, Aegis) as much as possible.
