This is a Human-based aggro / prison deck playing enough hatebears and disruptive creatures that plays a small number of spells. This deck is based strongly on the builds by Sam Castrucci and Jogee (mtgo) seen in the vintage meta game. If it is powerful enough to see play in vintage it could have a chance in legacy. However, color fixing and acceleration must be taken into account as there are no moxen when adapting the legacy version. Also, the hatebears need to be wider as there are more than the only four prevalent decks in legacy than vintage. Artifact hate slots were thinned out since MUD is not a strong concern in Legacy, while storm and dredge hate slots were kept the same. Nevertheless, the deck is still in progress, but here is a current list.
This particular list is built so that Unclaimed Territory can cast any creature in the entire deck alongside Cavern of Souls. The only non-human here is Phyrexian Revoker, but is only uses the colorless mana.
Mana Confluence is...mana confluence, a rainbow land in a five color deck. It is technically better than City of Brass, but I've yet to see Tangle Wire-like effects become mainstream in legacy.
Both Thalias' roles are similar to their role in most decks they are played in such as Death and Taxes. A resistor effect combined with Wastelands and disruption to slow down combo while being a threat at the same time.
Harsh Mentor, Meddling Made, and Kitesail Freebooter are disruption creatures that are also threats.
Kambal and Scab-Clan Berserker give this deck protection against the broken combo decks by making most "one big turn" type strategies impossible to utilize. The brainstorm, ponder, preordain builds that many Legacy decks use also become a liability when facing down Kambal, Consul of Allocation or Scab-Clan Berserker.
Manic Vandal isn't incredibly impressive, but it's a Human that can take out an artifact. Not sure if it needs to stay in the Legacy version, as it was main deck include for vintage due to the widespread use of Moxen and MUD archetype cards.
Aether Vial is pseudo-acceleration to replace the Moxen and allows creatures to be put into play at instant speed. As a result, Null Rod is removed from the main deck. Also, Null Rod is not as strong in Legacy as it is in Vintage. Once again, because there are no Moxen in legacy and MUD is not the strongest deck in Legacy.
Reflector Mage is one of the only ways this deck has to deal with an opponent's creature. This is an important ability that could save your life when you're fighting against a Griselbrand or a Spaghetti Monster.
Mayor of Avabruck and Thalia's Lieutenant act as anthem effects.
Noble Hierarch is great mana fixing and acceleration.
Dark Confidant is the only source of card draw advantage; the mana curve of the deck is low enough to use Dark Confidant.
The sideboard is mostly made up of additional hatebears.
Containment Priest and Grafdigger's Cage are good against any cheat creature into play decks such as Natural Order, Show and Tell, and Reanimator builds. (Grafdigger's cage doesn't work against Show and Tell).
Aegis can also do some work against combo decks that win with Tendrils of Agony, but good protection against any discard based deck that may also use cards like Liliana of the Veil and Diabolic Edict. It is a Leyline of Sanctity on a creature.
The Pontiff's ability to shrivel the opponent's creature's power and toughness is good against decks like Elves, Death and Taxes, and Merfolk that can wipe the board without wiping our side of the field.
Melira, Sylvok Outcast is kind of narrow and only good against infect. It can probably be removed since Infect is on a downtick in popularity lately. But it is good to know there is a human that exists for infect if it it rises in popularity again.
Grand Abolisher plays a bit like a Defense Grid. Good against blue decks with a lot of counterspell effects. Sometimes, Cavern of Souls in not enough, or cannot be found naturally.
Why is there no Champion of the Parish or Mother of Runes? This looks more like standard or modern than legacy. Merfolk decks can usually do what humans do - boost each other - but better because they have more mana-cheap cards to boost everything by +1/+1 or can be unblockable, and they have counter spells and can splash for whatever spot removal they want. If your mana base is already 5 colors, there's already better decks that can run 5 colors.