attunement slots - DnD Attunement 5e explained - Wargamer samurai 888 katsumi slot machine

Increasing Attunement also increases the amount of Attunement Slots your character has at the following breakpoints ...

If you're a spellblade type, and you want to go Sword-Focus, that leaves you with two of your attunement slots consumed just with your hands.

There are two rings that grant additional attunement slots (one each): These are the "White Seance Ring" and the "Darkmoon Seance Ring." (If I got that wrong, feel free to correct me.).