Elden Ring: How To Get Rock Sling

screenrant.com:

Rock Sling is an offensive Spell in Elden Ring that uses Gravity Sorcery to conjure three heavy boulders and launch them at foes. Unlike Glinstone Sorceries, Rock Sling deals Physical Damage and can potentially stagger enemies as well. Furthermore, when paired with the Meteorite Staff, this Spell can wreak devastation in combat at both high and low levels. However, Rock Sling's two main disadvantages in Elden Ring are that it is costly in FP for low-leveled mages and has a lengthy cast time.

Nevertheless, Rock Sling is one of the best early-game Sorcery Spells since it can be acquired from the very start of the player's journey. Once spellcasters understand its limitations in range, FP cost, and velocity pathing, the Spell becomes a must-have for any developing mages. The Rock Sling's location is in the heart of Caelid, the Scarlet-ridden Swamp of Aeonia. While this area is far above the recommended difficulty for low-level adventurers, the Sorcery, including the Meteorite Staff, are extremely easy to acquire.

Related: Elden Ring: Oridys's Rise Puzzle Solution

Starting from the Site of Grace at The First Step, travel eastward towards the expansive lake. Try staying near the southern coast, as venturing too deep into the lake's center will cause Flying Dragon Agheel to descend upon the player. Head to the Dragon-Burnt Ruins and enter the underground entrance on the northern side. The area will be guarded by several zombified humanoids and rabid dogs, but they can be easily bypassed by rushing into the crypt.

A mischief of rats crawls within the chamber beneath, but the player will be invincible to damage if they dash to the door ahead and open it. Inside will be a chest that will teleport Tarnished to the Sellia Crystal