I am not good at namegiving, so the name will be incomplete
.
Shrine/Altar of ...(cool sounding name of a god or something from the dom3 mythology)
A commander may enter this Site for 1 turn to preach and give the god gifts. Gifts can be anything like gems, troops, Gold etc. etc..
Depending on what the commander spent he may get empowerments that are thematic. The amount of spent stuff also matters.
The same commander can preach and spend multiple turns and always get additional effects.
There is a complex formula system behind it which includes random dicethrows and a chart.
Simple example:
A D100 is thrown.
Chart for spending Deathgems:
0 Deathgems spent:
Diceroll:
1-10: The god is annoyed by the blasphemy of the hero and throws him into hell.
11-50: The god punishes the greedy hero. Random effect like lose 1D6 HP, get a random affliction or something like that.
51-90: Nothing happens.
91-100: The hero gets a small gift which can be anything like a weapon, extra health, another equipment slot etc. etc..
If the hero instead spends 1-100 deathgems the diceroll chart is modified that he gets better results, e.g. like this:
1: Hero dies
2-20: Hero gets punished
21+: Good effects, thematic to the deathgems, like getting lifeleech, etheralness etc..
Then additional charts for ppl who spend even more gems.
But always there is a small chance included that something bad happens to your hero.
So it is a big gamble what you get. It may be more than worth the spent gems or it may be a waste.
Inspired by various Rpgs, iirc there were 1 or 2 such spells in one of the Black Isle D&D games like BG 2 and iirc the Chaos faction in Lords of Magic had such spells too.