The Witch is a mod for Darkest Dungeon, created by ErlKing.
Background: Selfish pretender of proper mage Witch have to call upon entities who feed on human nature. While lacking years of training and magical talent she trade health, longevity, bits of soul, often not her own, to loan power, for a time, again and again. Promise of True magic is what bring witches to this town, hope to get real power and be finally free.
The Witch should appear as a hirable hero in the stagecoach. It might be a good idea to start a new game (since if the mod file were deleted, having an Witch on your roaster might crash the game).
Simply copy each of the folder into the DarkestDungeon game folder (usually here C:\Program Files (x86)\Steam\steamapps\common\DarkestDungeon\)
This should copy over and add some files to each of the folder. See below for instruction how to add the Effects and Localization.
It would also be a good idea to back up some files before hand.
Note: consult the effects_That_Need_To_Added.txt file for additional instructions or the game will crash!