Mythic in historic with an archetype I haven't seen anyone else play: Boros legends
Flowering of the White Tree, Mox Amber, Merry Esquire of Rohan, and the channel lands provide very strong payoffs for the deck being almost entirely legends. The legends can provide most of the utility and card advantage you need while leading to some very quick kills, especially with General Thunderbolt Ross, White Tree, and Mox Amber starts which can kill on turn 3.
For your opening hand, look to always have a 1 drop unless you can double-spell on 3 with a mox amber. The best hands will contain mox amber, white tree, or 1 drop ---> merry.
The best matchups are black midrange decks like dimir frog, and slow combo decks like belcher or valakut. The worst matchup is gruul berserk, which I am 0-5 against and is nigh unwinnable. Most other popular decks (ruby storm, UW flash, Phoenix, lightpaws) are even matchups.
If you like creature decks you should check this out, it's a lot of fun and I imagine the deck will get new cards just about every set given WOTC's propensity to print so many legends these days.
For an up to date list check out the decklist on moxfield
The current list, copiable to arena :
Companion
1 Lurrus of the Dream-Den
Deck
1 Basri, Tomorrow's Champion
3 Chain Lightning
1 Eiganjo, Seat of the Empire
4 Flowering of the White Tree
2 General Thunderbolt Ross
2 Hawkeye, Master Marksman
4 Inspiring Vantage
2 Inti, Seneschal of the Sun
2 Isamaru, Hound of Konda
2 Kari Zev, Skyship Raider
2 Kellan, Planar Trailblazer
2 Kytheon, Hero of Akros
4 Merry, Esquire of Rohan
4 Mox Amber
1 Norin, Swift Survivalist
1 Plains
4 Plaza of Heroes
4 Sacred Foundry
2 Sokenzan, Crucible of Defiance
4 Sunbaked Canyon
2 Thalia, Guardian of Thraben
3 Thraben Charm
2 Zack Fair
2 Zurgo Bellstriker