Hyakki Yagyō [Legendary Beast]

As a slaver, my goal is to have humans as my beast. It feels thematic, and it could essentially just be monkies.

Name: Hyakki Yagyō translated as Night Parade of One Hundred Demons
Tier: A
Type: Swarm/Parasite
Species: Amber-banded Broodsac
Appearance: A parasitic flatworm that lives within human beings, gravitating towards the eyes. Victims of the yellow-banded broodsac have pulsing, amber eyes. As many as ten thousand can be sustained in tact around a primary host. The hosts vision is tinted yellow and takes D-tier damage every round from the host taking nutrients from the host.
Beast Traits:

Trait Name: Human Hosts
Trait Tier: A Tier
Trait Requirement: Evolution of Amber-banded Broodsac
Trait Description: The parasitic flatworm has partially evolved to living in human beings.
Trait Effect: The Hyakki Yagyō beast lives within human beings, allowing the beast to use the body of humans as a beast swarm.

Trait Name: Imparted Magoi
Trait Tier: A-tier
Trait Requirement: The owner must be infected, becoming the Primary Host.
Trait Description: The magoi of the primary host lives within the swarm of Hyakki Yagyō.
Trait Effect: Spells from the primary host may originate from any of the hosts within a 100M radius of the primary host.

There is no double dipping in types for beast tamer, it only maintains one classification. So far this seems a little messy man.

Flatworms range in length from about 1 millimeter (0.04 inches) to more than 20 meters (66 feet). Even at the bare minimum, you wanted 10 thousand of them inside you as the host body, times 0.04 by 10k that's 400 inches, aka 10 meters. you can't hold all of that by yourself.

parasite/symbiotes are usually stand-alone.

human hosts is too simple, you can probably had a set of infectees at a time, they would have to be npcs, and the rank of them would dictate it as well. 1 A-rank or 2 b ranks, (you get it by now), it would have to tally up to the rank of the trait itself. something extra might also have to be added in in terms of infection method and total control. do they have to be in a death like state, how do they act afterwards? does it have to be verbal commands, what happens after? Can't just happen instantly, but once you got them, you got them, until they are gone.

Imparted Magoi- this would have to happen first before you even use human host, which that trait is too barebones for us to even consider right now. and even if we did. it would be no more than 1/3 of your magoi you are parting with for the extended host to have that reserve to use. cooldown won't change, and using it as a conduit for extended spellcasting. basically the infected will be an extra wand for that portion of magoi that worm has.