Crushing yeti

Lives in caves and abandoned mines, this Yeti loves to emerge from the darkness and attack adventurers and explorers. The Yeti 

Mine shaft. It looks normal, but the second the adventurers step 5 feet from the door and are in the mine, the Yeti releases a ton of Stone in the entrance that require a DC 20 strength to get through (each group has to get a average of 20 or they fail. It is impossible for one person to do). Than the Yeti uses his legendary and mythic actions to attack. Otherwise, go to the $$ symbol

Lair Actions

$$On initiative count  7 or lower (if you tie with initiative you win and this doesn't happen. Go the #$ symbol), the Yeti pulls a lever, which he can be spotted doing with a 15 or higher and fought with a 17 or higher. If all players roll a 10,9, or 8, the Yeti does a lair action.

He either makes a rock fall on any players who can be surprised, the rock does 3d4 bludgeoning damage or

creates a 20 ft deep hole filled with 3 swarms of Swarms of Poisonous Snakes snakes and 3 nozzles in the side that every 5 rounds, do 1d4 fire damage to every player. Multiply the dice amount by the number of players (3 players, 3d4 fire damage, 4 players 4d4, ect.) Once the snakes are killed 3 potions of greater healing and 2 potions of lesser healing are produced. A DC 10 acrobatics or DC 10 strength (if all players help. It is raised from a DC 10 to a DC 15 for a player doing it themself. Than he Yeti attacks and once killed, the rest of the dungeon is the GM`s idea.

#$ the Yeti is confronted and when killed, 3,000 gold falls down

LOOT: 3 +3 crystal swords(magical), 750 gp per person, and 3 javelins of lightning.