Fixed in 1.5.1
Same issue as Bug #1402.
The cleric’s Serpent Staff is supposed to leech health from enemies at close range. In the Scattered Evil RPG system it is typical to have well over 100 max health early in the game. However, if the player’s health exceeds 100, the health leech ability reduces it to 100. (When testing this, my cleric’s max health was 795 at lvl 16.) Therefore the only time this ability is useful is if the player has less than 100 health.