Ryoko's Guide to the Yokai Realms, pg 218
You are practised in the ways of fighting colossal creatures, granting you the following benefits:
• Mounting a creature costs you only 5 feet of movement, rather than half your speed.
• You can brace* yourself by spending only 5 feet of movement, instead of half your speed.
• You have advantage on ability checks to identify vulnerable areas**.
• You ignore the difficult terrain caused by moving on a creature more than two sizes larger than you.
• Immediately after a creature you can see that is at least one size larger than you hits or misses you with a melee attack roll, you can use your reaction to make a weapon attack against that creature.
*See page 8
**See page 6