UPDATE: managed to solo trampeled plains in 19 mins (whole level in 19 mins including a fight with 2 minibosses pre main boss)
Tactics: use the wall! get them to charge you into the wall they will then try to jump back when they miss thier attack but they cant because they will just jump back into the wall giving you enough time to get a scythe 3 in and marking them with death label.
Summoning a wisp to distract 1-2 of them is not a bad idea either and as they are knocked down VERY easily the wisp might even knock them down for you sometimes.
I'll post a video later, but all in all its not worth your time, your time will be better spent soloing red tyrant with 4 people oath (55k EXP per run if done solo), its much better exp/gold per run and untill you can do red tyrant solo macha prince.