How do Mounts work?
Horses to be used as steeds can be purchased from Mailee at #unfamiliar-familiars. Creatures other than horses require special saddles in order to be ridden, and undomesticated animals/monsters may only be ridden during quests / arenas at DM discretion or if the statblock / item description says they can be ridden.
All the listed options in the Find Steed / Find Greater Steed are permitted for those who have that option. If you would like a steed that is not listed in there you can either use a statblock for one of the listed mounts and reflavour it as a similar creature, as long as any special attacks / abilities make sense. If you would like a statblock different from one of the listed mounts for your custom steed then submit a request to #request-board, the DMs will then discuss what would be an appropriate statblock and whether it would be a permissible mount.
Note: Only non-hostile creatures at least one size category larger than you have any chance of being ride-able.
While mounts are in combat there are two options for how they act: Controlled or Independent. Most of the time while you are riding your mount, it will be a controlled mount. A controlled mount is effectively an extension of your character. It moves during your turn and the mount can only take the Dash, Disengage, or Dodge actions. It can still take bonus actions and reactions including attacks of opportunity, provided it is physically capable of doing so. E.g. a warhorse requires its hooves to attack, so would be unable to make an AoO if its feet are stuck in quicksand or mud. Controlled mounts are controlled by the player.
Intelligent creatures or wild animals are typically always independent mounts, but in special circumstances - such as the Find Steed spell - may consent to become a controlled mount. Independent mounts roll their own initiative and act on their own turn, but have access to all actions including making attacks. However, you may be required to make an ability check to get an independent mount to follow your instructions. Independent mounts may choose to flee combat, or throw off their riders of their own accord and are controlled by the DM.
Items and Mounts
Controlled mounts can wear barding and other equipment designed for them, but cannot wield weapons nor use magic items (except items specifically designed for mounts). Independent mounts may be able to use other objects, at DM discretion.
Frequently Asked Questions
D&D 5e is not especially good at explaining mounts and mounted combat, here are some of the most common questions.
How big is my mount?
A Medium creature fills a 1x1 square on a battlemap and can only be ridden by Small or smaller creatures.
A Large creature fills a 2x2 square on a battlemap grid, while riding a Large mount you are treated as occupying all of those squares for the purpose of attack reach and AoOs.
A Huge creature fills a 3x3 square on a battlemap grid, while a Medium or smaller creature is riding a Huge mount you are normally treated as occupying the entire 3x3 square for the purpose of attack reach and AoOs. However, your DM may choose to treat you as occupying the central square of a Huge mount - be sure to ask which rule they use.
Can “X” be my mount?
In general, creatures that can fly, or cause status effects (other than “prone”) such as ‘poisoned’ or ‘restrained’ are not allowed as mounts, unless given by a DM for use only during a specific quest.
Example: “I ride up to the Orc and attack him with my sword.”
Controlled mount: the mount moves as part of your turn, you use your action on your turn to make your attack making two (or more attacks) if you have the Extra Attack feature. The mount cannot attack, but may Disengage and continue moving after you have attacked.
On your turn: You use your movement and bonus action, then Hold Action to attack once in range of the Orc, then instruct your mount to approach the Orc.
On mount’s turn: The mount uses its movement to get within 5ft of the Orc, triggering your held action. You use your reaction to make a single attack against the Orc, (Extra Attack only applies to attacks on your turn.) Your mount can then make its attack against the Orc.