Earth Elemental

An earth elemental on the party's side almost always means a summoner: a druid with Conjure Elemental, a wizard who paid a Plane of Earth gate-keeper, a cleric whose temple gifted them a bound servant for the dungeon ahead. Treat the elemental as a tool the caster aims, not a teammate the party negotiates with. It speaks Primordial (Terran) and nothing else, so most of the party cannot give it orders directly. The summoner gives one short instruction per turn and the elemental executes.

Use Earth Glide aggressively. The elemental should never approach a fortified position above ground. It dives at the start of its turn, surfaces inside the enemy line on the next turn, and opens with two Slams at +8 for 14 average each. Siege Monster doubles damage to objects and structures, so if the obstacle is a door, a wall, or a barricade, the elemental is your battering ram. A 30-foot burrow speed plus the ability to ignore stone means siege is fast and quiet.

The elemental will not climb a ladder or board a small boat, and a wooden bridge it could fall through is a hard stop. Plan around its weight and its lack of judgment. It also will not protect a fallen PC unless told to, because Int 5 means it does not improvise. The party's job is to shout the right command at the right moment, and the GM's job is to make the elemental obey the literal words.

When the spell ends or the contract closes, the elemental sinks back into the stone without a goodbye. Describe the floor going still. The room feels emptier in a way the party cannot quite name.

An earth elemental is the encounter you build the room around. Earth Glide lets it burrow through nonmagical, unworked stone without disturbing the material, which means it does not enter combat through a door. It comes up through the floor, in the middle of the party, after the front line has already walked past. Plan the arrival before you plan the fight.

On its first turn after surfacing, lead with Multiattack: two Slams at +8 reach 10 ft. for 14 average bludgeoning each, and pick the squishiest two PCs in 10 feet. If the party has clustered, swap one Slam for Rock Launch at +8 range 60 ft., 8 average bludgeoning, and Large or smaller targets go Prone. Use Rock Launch on the back-line caster who stepped out of melee range thinking they were safe. The Prone is the real damage: it costs them half their movement to stand, and it gives every adjacent ally advantage on the next swing.

Tremorsense 60 means stealth is meaningless on the ground, and the immunity list (Poison, Exhaustion, Paralyzed, Petrified, Poisoned, Unconscious) shuts down most save-or-suck spells. The vulnerability the party can exploit is Thunder. A bard with Shatter, a sorcerer with Thunderwave, or a smart fighter with Thunderous Smite doubles damage. If the players notice and switch tactics, reward it; if they do not, the elemental grinds them down through 147 HP and AC 17. With Int 5, the elemental does not retreat or parley. The summoner might call it back. The elemental itself just hits things until it is dismissed or destroyed.

Run the elemental in a place that matters to its arrival. A flagstone floor that bulges and cracks before initiative is rolled does more for the encounter than any monologue. Let the party hear the stone groan for ten seconds before the first attack lands.