Mortal Shell is a Souls-like game with some very unique concepts going on. Aside from the challenging combat and spooky setting, there’s something else lurking beneath the depths of its dreaded swamps. As you start collecting items, you will notice one of these hidden mechanics pretty much right away. If you look at the stat page for any equipable item, you will notice an odd thing called item familiarity.
Item familiarity in Mortal Shell is all about how useful an item is to your Shell. And given that this game is about taking over other bodies and stealing their abilities, it should be pretty obvious what this means. Yes, in case you didn’t already know, this game is about possession. The short version is that the more you use an item, the more useful it becomes to you.
You can find items anywhere, be they from enemies or hidden treasure chests, and each one is affected by Item familiarity in Mortal Shell. Each time you use an item for the first instance, you will get to know what it does. The stats of an item are hidden until you use it. And the more you use an item, the more interesting it’s effects become. The tooltip for the item will reveal itself on the first use, and this applies for both healing and equipable items. Any useable item in the game can be affected by the item familiarity system.
In some cases, items will change completely. For example, the Tarspore is one of several plants that grows around the game world. The plant will inflict the player with a nasty poison debuff for 16 seconds on first use, with lesser effects for the next two uses. On the fourth use though, it becomes much more interesting. After that, it will then grant you immunity from poison damage for two minutes on use.
So once you have an item, get to using it. Each item has a Familiarity “punch card” so to speak. When you use that item, you’ll add to its overall Familiarity rating. To max out an item’s Familiarity, you’ll need to use it multiple times, as many as 10 times for some items.
Once its Familiarity was maxed, new information was added to its description in the game’s Compendium. To view an item in the Compendium, press “I” to open your inventory. At the top, select Compendium, then scroll through the items until you find the one you want to check out. From here you can see what effects you have unlocked for any item.