nightspaladin
Explorer
Personally, I like 2 options presented here mix together. I'd go with a concentration based radius from the cleric that deals X radiant damage every round to undead, and all undead in the radius are at disadvantage to attack rolls. Instead of the typically D&D/pathfinder, blast of channelled energy that it is often described as, it is a beacon of light and life, that sears all of those that wear false life and forces them to avert their eyes in it's presence(thus the disadvantage)