In medieval times people believed in gods and witches and magic, etc. How about we start emulating this here as well? It'd be an enormous system but one that would expand upon the game vastly. The components would be: religion, witchcraft, magic.

Religion would be the straightforward one. Crosses, holy relics, bibles; shrines, altars, monuments. Anything connected to dieties and holyness. This part would allow players to cast blessings upon players, claims, blocks and lands. They'd require players to perform sermons and make sacrifices to gain God's trust.

Witchcraft would be connected to alchemy in majority. Voodoo dolls, wands, fetishes; cauldrons, cult sites, occult tables. This is the darker side of mysticism that would allow to brew special potions, cast curses or perform strong rituals at night. Witchcraft would require knowing potion recipes and item combinations to create special ingredients and items. It would also take considerable time to complete (up to hours even).

Magic is the classic one, but heavily simplified. No things as fireballs, meteor showers or lightnings; only simple spells. Wands, staves, scrolls; libraries, towers. This is the neutral aspect of fantasy that would allow player to cast simple spells and enchantments, both beneficial or harmful. Magic would use classic mana system that regenerates over time. The amount and regeneration speed would be heavily influenced by amount of special items that are present on the claim.