Optional actions players can take during their turn~ I'd like to use- Will update from page numbers to actual descriptions.

CLIMB ONTO A BIGGER CREATURE
If one creature wants to jump onto another creature, it can do so by grappling. A Small or Medium creature has little chance of making a successful grapple against a
Huge or Gargantuan creature, however, unless magic has granted the grappler supernatural might.
As an alternative, a suitably large opponent can be treated as terrain for the purpose of jumping onto its back or clinging to a limb. After making any ability checks necessary to get into position and onto the larger creature, the smaller creature uses its action to make a Strength (Athletics) or Dexterity (Acrobatics) check contested by the target's Dexterity (Acrobatics) check.
If it wins the contest, the smaller creature successfully moves into the target creature's space and clings to its body. While in the target's space, the smaller creature moves with the target and has advantage on attack rolls against it. The smaller creature can move around within the larger creature's space, treating the space as difficult terrain. The larger creature's ability to attack the smaller creature depends on the smaller creature's location, and is left to your discretion. The larger creature can dislodge the smaller creature as an action- knocking it off, scraping it against a wall, or grabbing and throwing it- by making a Strength (Athletics) check contested by the smaller creature's Strength (Athletics) or Dexterity (Acrobatics) check. The smaller creature chooses which ability to use.


DISARM
Use a weapon attack to attempt to knock a weapon or item
from target’s hand. Make an attack roll contested by the
target’s STR (Athletics) or DEX (Acrobatics) check. On
success, target drops weapon/item. You have disadvantage
on your attack roll if the target is holding a item with both
hands. The target has advantage on the ability check if it is
larger than you, or disadvantage if it is smaller than you.


OVERRUN
Force your way through a hostile creature’s space by
attempting to overrun it. As an action or bonus action,
make a STR (Athletics) check contested by the target’s STR
(Athletics) check. If you are larger than your target, you gain
advantage, if you’re smaller, disadvantage. On success,
move through the hostile target’s space.


TUMBLE
Tumble through a hostile creature’s space. As an action or
bonus action, make a DEX (Acrobatics) check against
target’s DEX (Acrobatics) check. On success, move through
target’s space.


SHOVE
Use an attack action to shove a creature to knock it prone
or move it away from you. Your target must be no more
than one size larger than you, and within reach. Make a STR
(Athletics) check contested by target’s STR (Athletics) check
or DEX (Acrobatics) check. On success, knock the target
prone or push it 5ft away from you.

Shove Aside: Take disadvantage on your ability check to
move target 5ft to a different space within your reach.