OSR: Boss Fight: The Stone Cobra Guardian

Stats: as a standard Stone Golem, or an Ogre with a resistance to slashing and piercing damage. Slow moving and bulky.
Appearance: a stone knight clad in carved armour. It wields a huge dented sword in one hand. Its other hand is empty when combat begins.
Wants: to protect the rest of the Tomb of the Serpent Kings and kill any interlopers

Attacks 

Each round, the Stone Cobra Guardian can perform one of three attack patterns.

1. Shield Draw. The Guardian calls to a shield attached to the wall of the arena. The shield deals d6 bludgeoning damage (Save vs Dex negates) to any creatures between it and the Guardian. The Guardian holds the shield in its empty hand, granting it +1 Defense. The shield can be sundered as normal (reducing incoming damage by 1d12 and destroying the shield).

2. Leap and Slam. The Guardian leaps into the air and slams down 5' to 20' away from its starting position. It will not land directly on creatures, but any adjacent creatures take 1d4 damage, Save negates. Creatures that take damage are knocked prone.

3. Twin Slash. The Guardian swipes at two targets with its sword. The targets must on the same facing (front, side, or rear) and must be adjacent to the Guardian. This is a normal attack, dealing 1d8+strength bonus damage on a successful hit.


The Stone Cobra Guardian will be encountered first as a boss fight, but may end up becoming a semi-normal enemy for high-level groups. It fights in a very Dark Souls way. Over a long fight, the patterns will become obvious to players, and can be used to their advantage.

Akhnout, François-xavier Huet

My group defeated it using the Mobile Rod they found in the pool of dissolved mummy goop in Room 11. The Mobile Rod is the opposite of an Immobile Rod, and pushed the Guardian backwards and into the chasm. The Guardian did chop off Tito's leg.

Room 19 is designed for the players to flank the Guardian, or flee (it can't pursue up the stairs) or push it out into the chasm, or flee past it and hope it doesn't follow them (it will). The shields on the walls can be used by the PCs as well, and some of them are valuable if looted and disassembled.