Madness is one of the new status effects that you can make a build around. This status effect acts like frost and bleed. It has a bar that builds up and when it gets full, it causes you to lose a large amount of health. The Howl of Shabribri is one of the few madness spells you can get your hands on. This spell causes your character to emit a loud scream that inflicts madness on nearby foes. Here is where you can find the Howl of Shabribri incantation in Elden Ring.
To obtain this incantation, you first need to make your way north to Liurnia. This can be done in two ways. You can either make your way through Stormveil and defeat Godrick, or you can go around Stormveil by following the cliffs to the east. Both ways will bring you to the Lake-Facing Cliff Site of Grace.
Once you reach Liurnia, start traveling north across the lake area and past Raya Lucaria Academy. You will need to travel up onto the land where the bridge connects to the north. You can easily reach this area going up the hills connected to the lake to the west of where the bridge connects. Once you get up onto the land, follow the cliffside up into the mountains. After a while, you will start to see a tower with a massive red glow that appears above it. This is the Frenzy-Flaming Tower. Getting close to this tower will cause madness. You will need to go inside the tower. Run up to the tower and stay behind objects whenever the light is active. Climb up the ladders and you will find a chest that contains the incantation.