The blessing of Virgin Mary. The persons who receive this will benefit from damage reduction for a limited amount of time.
The reduction is 1/2 on normal PvM maps and 1/3 on PvP maps. It is disabled in WoE and GvG maps.
Casting Kyrie Eleison on someone that has Assumptio will cancel Assumptio, likewise casting Assumptio on someone with Kyrie will cancel Kyrie.