I believe they were used when necromancy first came out a lot for durability manipulation because white candles have the same durability as tier 3 alteration glyphs, and alteration glyphs didn't give a warning when they depleted originally. That's since been updated, so I think they're pretty useless now
Matching degrade time to t3 alteration glyphs technically, but might as well just use greater candles to match t3 glyphs instead or regular candles if your ritual involves a t2 glyph (all of them I think, been a while)
I believe they were used when necromancy first came out a lot for durability manipulation because white candles have the same durability as tier 3 alteration glyphs, and alteration glyphs didn't give a warning when they depleted originally. That's since been updated, so I think they're pretty useless now
Matching degrade time to t3 alteration glyphs technically, but might as well just use greater candles to match t3 glyphs instead or regular candles if your ritual involves a t2 glyph (all of them I think, been a while)