Ritual modifiers

Modifier	Increase or decrease to effective bonus
Your god's high altar	+12
Actively worshipping	+7
Rain/snow/sleet (Pishe)	+7
Carrying fluffy items (Gufnork)	+7
Fluffy room (Gufnork)	+3
Wearing 3 stylish clothes (Gapp)	+4
Stylish surroundings (Gapp)	+3
Indoors (Sandelfon)	+7
Room with some water (Fish)	+7
Underwater (Fish)	+14
With 3 other priests (Hat)	+16
At other deity's high altar (Hat)	+9
Fighting (Sek)	+5
Ritual assistance set to 1% ("the hand of <deity> guides you")	+3
Near high altar	+3 to +9
Far from high altar	-2 to -8
1 priest minion	-4
2 priest minions	-8
3 priest minions	-13
4 priest minions	-17
Out of alignment	-5
Performing from faith rod	varies, but high penalty
Drunk (except Hat)	-33
Poisoned	-33
At high altar of another deity (except Hat)	-45
Witch/wizard-owned area	-45

Rituals are harder or easier, and cost more or less gp, depending on the circumstances under which the ritual is performed. You are informed of these bonuses or penalties when performing a ritual.

Bonuses

All deities

You'll get a bonus if...

• You are at a high altar of your deity.
• You're near a high altar of your deity. You seem to visibly get the bonus if you're in the same city as a high altar, or within a few miles of one.
• You have been "actively worshipping" your deity--in other words, if you've recently prayed or used a ritual burial command.
• The deity pool has been set to make rituals easier and more powerful ("the hand of Pishe guides you").

Unique

• Pishe: When outside in the rain, snow, or sleet.
• Gufnork: When you have enough (seven?  research If this has been marked on a page, it's because there was something that probably isn't known, that the person who edited the page thinks could be found out. Perhaps you could figure this thing out, and be famous evermore. ) fluffy items in your immediate inventory. Also, when you're in fluffy surroundings (your passage room or a room with at least 21 fluffy things on the ground).
• Gapp: When you're wearing three stylish items of clothing. Also, when you're in stylish surroundings (your passage room). These are mutally exclusive; the clothes bonus overrides the stylish surroundings bonus.
• Sandelfon: When you're indoors.
• Fish: When you're in water. Being underwater gives more of a bonus than being on the surface.
• Hat: When you're at another deity's high altar. Also, if there are at least four other priests in the room with you. NPC priests count for this.
• Sek: When you're actively in combat.

For specific rituals

• Mend is easier for Gappics when performed on a piece of clothing that matches Gapp's current favourite fashion.

Penalties

All rituals

You'll get a penalty if...

• You "sense that the gods have averted their eyes from this place", that is, you're in a Wizards Guild or Witches Guild outpost, or you're in real estate owned by a witch or wizard. This penalty seems to be larger for Resurrect than for other rituals.
• You're at another deity's high altar and are not a Hattite.
• You're poisoned.
• You're drunk. (Hattites get this penalty, but they also get a bonus for being drunk which seems to just cancel it out.)
• You're performing the ritual from a faith rod (the extent of the penalty may depend on your faith.items.rod bonus).
• You are far from a high altar of your deity.
• You "can barely sense the presence of <deity>", meaning you're nearly out of alignment.
• You're controlling one or more minions (totems, dust devils, dooms, or spectres)

Specific rituals

• Mend is more difficult for Gappics if the clothing you're performing it on is "an abomination unto Gapp". Clothing that's the opposite of a colour that's stylish seems to be specifically unstylish--so if red clothing is stylish, green clothing is unstylish.
• Feedback is more difficult if your hands are full.
• Major Shield is much more difficult if you're using a shield that is not a proper shield--that is, a "shield" that can't be used to block.
• Resurrect is rumoured to be more or less difficult depending on the manner of death, although this does not show up as a visible ritual modifier.  research If this has been marked on a page, it's because there was something that probably isn't known, that the person who edited the page thinks could be found out. Perhaps you could figure this thing out, and be famous evermore. 
• Rituals that require the power of sight are more difficult if it's too bright or dark to see. (See: Rituals requiring sight.)
• Rituals that have a distant target, such as Longsight, are more difficult if you "sense that your target is somewhere where the gods are not looking" (i.e., wizard- or witch-owned property).

External links

• DWPriests: Ritual modifiers