Selfish Basalt appears in Baths 7 and 8 of the Steamy Bathhouse within the Midnight Channel. While it is one of the few Basalts not resistant to Physical attacks, it resists Almighty (including an All-Out Attack). When defeated, it may drop Selfish Ornament. Selling ten Selfish Ornaments at Daidara Metalworks will unlock the Revenge Ring accessory in the shop. It also drops Coal, an item required to complete Quest 11: Acquire Coal.
Multi-target elemental spells will make short work of them, but they cannot be Dizzied and will still be able to take their turn if it comes up.
In Golden, Selfish Basalt appears in Baths 5 through 7 of the Steamy Bathhouse within the Midnight Channel. Selling eight Selfish Ornaments is enough to unlock the Revenge Ring. It may also drop Fluorite for trade at Shiroku Pub.
Persona Q2: New Cinema Labyrinth
Selfish Basalt appears in the 2nd Ave area of the first Theater, Kamoshidaman. It attacks with Physical skills. When defeated, it may drop Basalt Jewel and Basalt Rock. Basalt Jewel is used to create the Lightweight Rod for Ryuji, the Toxoid Saber for Akechi, and the Breeze Scarf for Morgana. Basalt Rock is used to create the Lumina Saber for Akechi and the Shoulder Vest male armor.
Selfish Basalt is the subject of Special Screening #1: Doing Our Part, wherein the party must defeat eight Selfish Basalts while wandering a section of the 1st Ave. The Craggy Boulder items they drop during the Special Screening unlocks the Healing Armlet in the shop, and completing the Special Screening yields the Trendy Shirt unisex armor.