The Mantelets will usually be installed in a ring formation around the fort in outdoor zones.
During a Campaign Battle:
Every person standing by the Allied Mantelet will get Refresh, Regain and Regen (each gives 3 per tick).
The effect wears off if you move more the 10 yalms far from the Mantelet.
Gradually loses HP at a steady rate until they finally despawn. This is not limited to Campaign and they will continue to lose HP after / before a battle.
Cure spells have no effect on them (however healing Blood Pacts such as Healing Ruby II still affects them).