I did this competitive deck by myself and got it up to mythic in mtg arena in a week, and has a 57% winrate (250+ games) in top tier.
This deck tries not to excel on anything but to be good at everything:
Good draw power (or get cards from the deck)
Good tokens presence
Good life gain
Good counters
Etc..
The deck focus mainly on the synergy of humans cards. It is a bit hard to master but quite fun after you have done it.
Ideally you want to play cards with Flash on their turn while increasing the ammount of humans you have in play and prevent them to be killed, then you can play Katilda, Dawnhart Prime so those humans can give you mana to play more creatures or to protect yourself using the different blue counters.
Eventhough the deck focus on humans for Katilda, Dawnhart Prime + Sigarda, Champion of Light
, is good to know that most of the humnas that run in the deck are also soldiers including the tokens from Torens, Fist of the Angels making Harbin, Vanguard Aviator and Myrel, Shield of Argive good bombs for the deck.
Normally you would like to keep Harbin, Vanguard Aviator and wait to have 5 soldiers, but it also good to know that if you have no blue lands then Harbin, Vanguard Aviator + Katilda, Dawnhart Prime
can give you the mana needed to play counters.
Another main card of the deck is Zephyr Sentinel it is an awesome card to protect your creatures when they are targeted but also an engine for many combos in the deck. For example, with Torens, Fist of the Angels in play, whenever you bounce a creature to your hand you are also getting a new token for the soldier count (Harbin, Vanguard Aviator) and for the human count (Katilda, Dawnhart Prime) and if you have Lunarch Veteran
its a good engine to gain life, also you can bounce Zephyr Sentinel + Zephyr Sentinel
so you can always trigger the ETBs effects.
Shanna, Purifying Blade is our engine for getting cards, you can protect her attacks giving first strike with The Wandering Emperor or using the first ability of Elspeth Resplendent also her third ability can give you a shanna with a shield which is good for protecting her.
At last having in mind that you might have a lot of mana from Katilda, Dawnhart Prime and all your humans since, most of them have flash there is a big gut that is awesome in the deck... Hullbreaker Horror you can cheat it using your humans to pay its cost, and all your flash cards will become good ways to interact with the opponent actions.
A small aspects to have in mind of Katilda, Dawnhart Prime is that she has protection from wherewolves so is good against werewolves decks and also against two werewolves that are commonly seen on meta Graveyard Trespasser
and Reckless Stormseeker
