if you want to use a social you can do it like this
/bcg //stance burn
that tells your group to change their merc stances to the burn setting.
now you can make it more advanced if you like
/bcg
//if (${Mercenary.State.Equal[ACTIVE]} && ${Mercenary.Class.Name.Equal[Wizard]} && ${Mercenary.Stance.NotEqual[BURN]}) /stance burn
That tells your toons if they have an active merc, that is a wizard and not in the burn stance, to put them in burn stance.
Now if you wanna do this in kiss you should be able to add a couple conditions and dps and buff lines to make it fully automated.
First we use buffs to set the stance to balanced so we dont start next fight with them in burn mode
INI:
Buffs1=command:/stance balanced|cond1
cond1=${Mercenary.State.Equal[ACTIVE]} && ${Mercenary.Class.Name.Equal[Wizard]} && ${Mercenary.Stance.NotEqual[Balanced]}
Then basically same idea in dps section
INI:
dps1=command:/stance burn|99|cond2
cond2=${Mercenary.State.Equal[ACTIVE]} && ${Mercenary.Class.Name.Equal[Wizard]} && ${Mercenary.Stance.NotEqual[BURN]} && ${Target.PctHPs} <= 50
notice we added a target hp check to get em to switch at 50%
so as long as you running kiss with these conditions and buff and dps lines, your wizard mercs should burn at 50% and out of combat switch back to balanced.
now there will be some overlap, as we dont take into consideration that you might be fighting two mobs, so they will move on ot next mob at burn stance. with that we could add another dps and condition that checks if they higher than 50, and burning then set it to balanced, you have enough information to create those lines though.,