Anathema's Chains

A thin chain made from a Steel Dragon's spines. 

Choose a target to mark as your Nemesis at the start of your turn. As long as you remain in combat with them, you can gain stacks of Vendetta. You gain 1 stack of Vendetta every time your Nemesis succeeds a saving throw for a spell you cast. Each stack of Vendetta increases your spell save DC by 1 for spells you cast against your Nemesis. If you choose a new creature to mark, all stacks currently held are lost. All stacks are lost at the end of combat, or when the current Nemesis dies.

Notes: Creature with the ability to cast at least one spell that has a saving throw