Mantra is a personal selectable buff similar to auras, which may also charge/boost other entities/items/skills.
Mantra mechanics are triggered when the character is at rest, gradually amplifying the effects of mantra or just enabling them(like e.g. meditation aura triggered by being idle for N seconds). (Mantra strength is proportional to time invested "charging").
Similar mechanics are encapsulated as "rest/recharge/regen action triggered when character is idle", however mantras are more versatile.
Types of mantra:
1.Buff: Applies or amplifies a personal buff/perk/stat
2.Healing: Healing mantras add hp/mana, remove debuffs or reduce their duration.
3.Aura: Charges an aura, increasing its radius/effect. The charge wears off with time proportional to mantra charge time.
4.Equipment: The mantra charges items to increase their stats proportional to duration of mantra activity. Similar to #3.