Riding and climbing unwilling creatures

A frequently occurring event is player characters attempting to ride, climb or balance on other creatures during combat. Presented are rules for a common framework addressing this as well as some feats tailor made to the idea.

A One-sided Grapple

Climbing, riding, or balancing on a creature is treated as a one-sided grapple and follows many of the same rules as grappling. Attempting any of these activities requires 2 actions, provokes attacks of opportunity unless you have an appropriate improved maneuver feat, and imposes the grappled condition on you if successful.
While climbing, riding, or balancing on a creature:

• The creature will have disadvantage on attacks against you
• You have advantage on attacks against the creature
• Bonuses to grapple maneuvers (e.g., feats or size modifiers) apply to your skill checks for these activities.

In general, the creature must be able to support your weight for you to attempt these actions. The base DC for the skill check is equal to the creature’s CMD + 10 (bonuses against grapples apply). Circumstances can modify the DC as follows:

• -5: The creature has rough scales, thick fur, or other features that provide good grip.
• +5: The creature has slick skin, smooth scales, or other features that hinder grip.

While climbing, riding, or balancing on a creature, you are flat-footed. Specific size requirements and restrictions for each method are described below.

Removing unwanted guests

A creature may attempt to throw you off as an action by making a combat maneuver check against your opposed skill check (corresponding to the method you’re using). If the creature succeeds, you fall prone in a random adjacent square.
Alternatively, if the creature moves using a swim, burrow, or fly speed you must make a skill check (corresponding to the method you’re using) to remain on the creature. The DC for this check is calcualted as follows:

• Swim or fly speed: 10 + 1 for every 5ft of movement
• Burrow speed: 10 + 2 for every 5ft of movement

Each subsequent move action taken by the creature increases the base DC by 2. On a failure, you fall prone in a random adjacent square at the end of the move action

Climbing

To climb a creature, it must be at least 2 size categories larger than you.

Riding

To ride a creature, it must be only one or two size categories larger than you. While riding a creaure this way:

• You must hold on with at least one hand or take a -5 penalty on your skill check.
• You have disadvantage on attack rolls anything other than the creature you're riding.
• You must make concentration checks to cast spells as though experieincing violent motion.

Balancing

To balance attop a creature, it must be at least one size category larger than you. The DC increases by:

• +10 for balancing on a creature that is only one size category larger than you.
• +5 for balancing on a creature that is two size categories larger than you.

Feats