Climbing Larger Creatures

If you are at least one size category smaller than another creature and you are within 5ft of it, you may attempt to climb onto it. If the creature is not willing, you must spend double the normal amount of movement and roll a Acrobatics (Dexterity) check contested against the creature's choice of Acrobatics (Dexterity) or Athletics (Strength).
If the creature occupies multiple spaces, choose one space the creature occupies within 5ft of you, you are considered to be on that tile. Area of Effect attacks still affect you while you are on top of other creatures. If the creature moves, you move with it, staying in your relative position.
If the creature deals damage to you or the creature becomes affected by knock-back, you must roll a Dexterity Saving Throw against 10+half the damage taken or if knock-back 10+half the feet knocked back, on a failed save you fall off.
If the creature's size category becomes equal to yours or smaller, your speed is 0 or you cannot move and the creature moves, you become affected by knock-back or the creature teleports or is teleported, you automatically fall off. When you fall off the creature, you take the number of size categories the creature's size category is above your own times d6 worth of bludgeoning damage and you become prone, in addition to extra fall damage if the landing location is lower than the ground location of the creature.
When you fall off or want to climb off the creature, you must choose an unoccupied space within 5ft of the creature to land on. If no space is available, you remain on the creature, but you become prone. Moving off the creature costs double the normal amount of movement, and its height is the number of size categories the creature's size category is above your own times 5ft.