This is the first draft of an artificer infusion designed in tandem with clockwork-themed specialty I'm working on. The artificer (and specialties) already have lengthy class features, and (I think) I've got everything I want for this particular specialty. So, some leftover ideas made it into infusions, like this one. This is a first draft and I would appreciate comments about wording, balance, and pertinence. (Some fluff of the homebrew world that goes with it seeped in the description. Please ignore)
Item: At least 100 gp worth of mechanical components
You've learned how to create a clockwork steed that serves you as a mount and a beast of burden, both in combat and out. The components you use serve as the creature's body and require 8 hours and access to thieves’ tools or smith’s tools to assemble. You determine the clockwork steed’s appearance when you create it. Aasimars of Kyshar typically use axe beaks as mounts, but some artificers prefer the shape of an elk, a giant lizard, or even a dragon.
The clockwork steed is friendly to you and your companions, and it obeys your commands. When you finish a long rest, you can nominate a creature (including you) within 30 feet of the steed. When you do so, the clockwork steed obeys the command of this creature instead. Only one clockwork steed can be created a time. If you create a new clockwork steed, the first one immediately crumbles into unassembled components.
The clockwork steed never flees from combat, rushes to attack, or otherwise act against your wishes. See this creature's game statistics in the Clockwork Steed stat block, which uses your proficiency bonus (PB) in several places.
In combat, a mounted clockwork steed acts on your initiative count and moves where you command it to go (no action required by you). If you don't issue any commands, the clockwork steed remains immobile and oblivious to danger. You can take a bonus action on your turn to command the clockwork steed to take the Dash, Disengage, or Dodge action. You can also command the clockwork steed to take the Shove action from its stat block with your bonus action. If the clockwork steed provokes an opportunity attack while you're on it, the attacker can target you or the steed.
The clockwork steed cannot regain hit points by spending Hit Dice after a short rest, or regain hit points and Hit Dice after completing a long rest, unless you are within 5 feet of the it and have access to thieves’ tools or smith’s tools, for at least 1 hour during that rest
Armor Class: 16 (natural armor)
Hit Points: 1 + your Intelligence modifier + 5 times your artificer level (the defender has a number of Hit Dice [d10s] equal to your artificer level)
Speed: 40 ft.
Saving Throws: Str +4 plus PB
Skills: Athletics +4 plus PB, Perception +1 plus PB
Damage Immunities: poison
Condition Immunities: charmed, exhaustion, frightened, poisoned
Senses: darkvision 60 ft., passive Perception 11 + PB
Languages: understands the languages you speak
Proficiency Bonus (PB): equals your bonus
Leap. The clockwork steed can jump, fly, or glide in short bursts, jumping a distance up to 40 feet in any direction if it moves at least 10 feet on foot immediately before the jump, of half as much with a standing jump. Each foot cleared on the jump costs 1 foot of movement.
Shove. Contested Ability Check: +4 plus your PB vs target’s Strength (Athletics) or Dexterity (Acrobatics) check (the target chooses the ability to use), reach 5 ft., one target no more than huge size. Win: target is prone or pushed 5 feet away (you choose).
Shift. When the rider of the clockwork steed is subjected to an attack dealing damage, the rider gains resistance to that damage and the clockwork steed takes the same amount of damage. The clockwork steed cannot use this reaction if the rider is subjected to poison damage.