Functions:

It will automatically mark every important interrupt/stun target once entering combat with them.
It will also mark any important interrupt/stun target before entering combat with them by mouseovering their nameplate.
You choose which marks it uses, but it will not replace placed marks on bosses/party/visible nameplates.
It will never override a mark that has been placed, as long as it is on anyone in the party or that nameplate is visible.
Configure which mob it should mark and which markers it should use in the 'Custom Options' tab.
Place mobs in different "marking groups" and choose which markers should be used for each marking group. Example: one group for melee kicks and one group for ranged kicks.

Credit to Reloe for the work on the old Ghuun Marker which this is built from.