Holy wrench

The holy wrench is a reward for completing the Rum Deal quest. If players have it in their inventory when they drink a prayer potion, super restore potion, or Sanfew serum, they will regain additional Prayer points, depending on their Prayer level.

The effect of the holy wrench is restoring an additional 2% of the player’s Prayer points when the player drinks a dose of any prayer restore potion. This means that each dose of the potion will restore 27% of your prayer on top of the base restore of 7, 8, or 9, instead of 25%.1 All numbers are rounded down to the closest integer as usual.

The holy wrench does not provide any prayer bonus.2
, The holy wrench can be used to imbue the Ring of the gods into the Ring of the gods (i) along with 650,000 reward points in Nightmare Zone. This does not consume the wrench. The Ring of the gods (i) shares the holy wrench’s effect. The effects do not stack.

Listed below is the gain per dose of potion when using a holy wrench at different levels.

from Holy wrench
, If a player loses their holy wrench, they can obtain a new one by talking to Davey on Braindeath Island. Having more than one holy wrench in your inventory does not further increase prayer gain.

Some players consider the wrench to be rather useless, as the wrench takes up an inventory space which could instead be used for a Prayer potion. However, with level 50 prayer, having a full inventory of prayer potions(4) will restore 2,128 prayer points (4 * 19 = 76, 76 * 28 = 2,128), while having 27 prayer potions(4) and a holy wrench will restore 2,160 prayer points (4 * 20 = 80, 80 * 27 = 2,160), or 32 more prayer points. Plus, the wrench does not cost anything to obtain, while prayer potions can be very expensive. It can be used effectively if the player doesn’t bring an inventory completely full of prayer potions, like when prayer potions are used with food, or where inventory space is not an issue.

For max capacity, use the formula (p/n) + 1 = s, where p is the amount restored per dose (without the wrench), n is the extra prayer points from the wrench, and s is the amount of potions you need where replacing one with a wrench doesn’t matter (for capacity). So, if you have more slots available for prayer potions than s, use a wrench for higher capacity.

At 99 prayer, the wrench begins to restore more prayer points per inventory than just potions when the player uses 17 inventory spaces or more. i.e. 16 prayer potions and a wrench restores more prayer points than 17 prayer potions whereas 15 prayer potions and a wrench restores fewer prayer points than 16 prayer potions.