Untrained Combat Maneuvers

Untrained Combat Maneuvers
These maneuvers can be used by anyone who is either wielding a weapon with which they are proficient, or using a skill with which they are proficient. If the character is not proficient with the roll required, they cannot use that maneuver.

Climb Onto a Bigger Creature
Climb onto a creature at least two size categories larger. A successful Athletics or Acrobatics check vs. the larger creature's Dexterity (Acrobatics) maintains the smaller creature's position. Every round, the larger creature can take an action to dislodge the smaller creature with the same roll. While so positioned, the smaller creature moves with the larger creature and has advantage on all attacks against it. To attack the smaller creature, the larger creature must be able to reach the place the smaller creature is clinging (DM's discretion) and the larger creature takes half the amount of damage it inflicts on the smaller creature.

Disarm
To disarm an opponent, the attacker rolls an attack contested by the target's attack roll (using no actions or reactions by the target). If the attacker succeeds, no damage is rolled but the target drops the weapon. If the attacker is attempting to force a target to drop an item that is not a weapon, they roll a Strength (Athletics) or Dexterity (Acrobatics) check against the attack. The attacker has disadvantage if the target is holding the object in two or more hands, and the target has advantage if it is larger than the attacking creature, or disadvantage if it is smaller.

Mark
When a creature makes a melee attack, it can also mark its target as a bonus action. Until the end of the attacker's next turn, any opportunity attack it makes against the marked target has advantage.

Overrun
When a creature tries to move through a hostile creature's space, the mover can try to force its way through by overrunning the hostile creature. As an action or a bonus action, the mover makes a Strength (Athletics) check contested by the hostile creature's Strength (Athletics) check. The creature attempting the overrun has advantage on this check if it is larger than the hostile creature, or disadvantage if it is smaller. If the mover wins the contest, it can move through the hostile creature's space this turn.

Shove aside
With this option, a creature uses the special shove attack from the Player's Handbook to force a target to the side rather than away. The attacker has disadvantage on its Strength (Athletics) check when it does so. If that check is successful, the attacker moves the target 5 feet to a different space within its reach.

Tumble
A creature can try to tumble through a hostile creature's space, ducking and weaving past the opponent. As an action or a bonus action, the tumbler makes a Dexterity (Acrobatics) check contested by the hostile creature's Dexterity (Acrobatics) check. If the tumbler wins the contest, it can move through the hostile creature's space once this turn.

Shield Wall
If one character is within 5 feet of another character that is struck by an attack or fails a Dexterity saving throw, the first character can use their reaction to give the second character +2 to their AC or their saves until the beginning of the first character's next turn.