I think god wrath is useful. If there was no wrath, then choosing a god would not be a big decision. Crawl is about making decisions now about things that will impact your survivability later on.
Gods accept worshipers to further the god's goals. In return, the player who abides by the god's goals gains access to abilities bestowed by the god. These abilities help the player help the player to varying degrees. Abandoning a god means that you just wanted access to the abilities, but did not care about the god's goals. You used the god as an invocation machine. They will get mad.
I think a god should punish the apostate
- in a way that does not conflict with the god's goals,
- using the god's existing powers, and
- and should strive to negate the advantages that were bestowed on the player.
And just for a reality check, the punishment should have a positive effect on the game play and try to prevent scumming and boring ways to avoid the consequences.
Here is a list of some ideas that I have come up with. I expect many of them will be unworkable.
Ashenzari should take away the knowledge that you have gained.
- Ashenzari should give you amnesia. Forgetting scrolls, potions and wands is easy to deal with. Forgetting enchantments on items and maps is a bit more difficult to deal with. Forgetting stashes can be quite a problem.
- Ashenzari should curse items. In addition he should randomly turn scrolls that remove curses into scrolls that curse objects. Maybe he should do this when you read the scroll.
- Ashenzari should keep you bound but not provide any of the benefits. This fits his goals.
Beogh should still support orcs, just not you.
- Beogh should upgrade orcs that the user encounters for the rest of the game.
Cheibriados is still not in a rush.
- In addition to slowing you, Che should prevent hasting or swiftness.
- Cheibriados should pick bad times to slow you.
- Cheibriados should also drain stats that he formerly boosted.
Elyvilon is still a pacifist.
- Should both dull and curse your wielded weapon.
- Should drain most or all of you invocation skills. (Elyvilon is often used to train this skill before switching to another god.)
- Break up fights by blinking or teleporting combatants.
- Turn monsters passive or just reducing the experience gained by killing them.
Fedhas Madash still encourages plant growth.
- Should also upgrade hostile plants to more dangerous plants.
- Reduce or remove experience gained by killing plants.
Jiyva is still mindless.
- Continue stat shuffling.
- Drain intelligence.
Kikubaaqudgha still wants legions of undead.
- Destroy holy items in your possession.
- Interfere with necromantic spells. Maybe even reduce your skill necromancy skill.
- Deny XP from kills of undead.
- Resurrect corpses as undead just after you killed them.
Lugonu is still rebels against any type of structure.
- Corrupt level you are on. (Imagine holing up in a corridor to fend off a crowd and then having Lugonu corrupt the level.)
- Make distortion weapons backfire if you still use them.
Makhleb still likes to destroy. You're just on the top of the list.
- Loose power and/or HP when killing a demon.
- Reduce or deny XP gain from killing demons.
Okawaru would like to see you loose a battle.
- Induce weakness (the counterpart of might).
- Induce slowness (the counterpart of haste).
The Shining One sees you as unholy from now on.
- Reclaim any holy item you have access to.
- Make you vulnerable to negative energy.
- Reduce or eliminate XP gain from killing holy beings.
Trog still hates magic.
- Randomly burn spell books you hold or try to memorize from.
- Make you go berserk after casting a spell.
- Increase exhaustion time after berserk and increase chance of fainting.
Vehumet still is all about destructive magic.
- Reduce your conjugation skill.
- Reduce power/range of destructive spells.
- Increase cost of spells.
- Boost enemy spell caster powers.
Xom is still insane.
- Maybe you can abandon him, but he will never abandon you.
- Bore him (and suffer his acts) until he looses interest in you.
Yredelemnul is still the god of death.
- Drain you.
- Mirror some damage to inflict back to you.
Nemelex Xobeh,
Sif Muna, and
Zin already have punishments consistent with their goals.
In addition, I think that some of these punishments should last the rest of the game.
This can counteract benefits (god gifts) that are not ever taken away.