This deck benefits immensely from the free multiplayer mulligan and will only further improve if the London mulligan system is adopted. Between Ugin's Conjurant and Recruiter of the Guard you have 8 ways of reliably finding an Ugin's Conjurant so all you need to do is mull for a Kirin or even keep your 7 if you think that you can win without one.
As for the lands, creatures and spells it doesn't really matter what you run. I posted a stock Hatebears deck but even if you don't have an optimal build it should still work. You could push the spirit theme with cards like Spirit of the Labyrinth and Eidolon of Rhetoric, you could field different kinds of Hatebears (think Grand Abolisher and Aven Mindcensor) on and on and on. 24x Plains would work just fine but I also like showcasing what my optimal manabase would look like.
This is the best home for the combo that I can think of and I mostly wanted it bring to the attention of anyone who wasn't aware of it.
As far as Hatebear decks are concerned there's countless ways to build the deck so it mostly depends on what you own and and what will work in your meta. Still, in general you should be sticking to the following cards:
What I like about his combo, is that it is very cheap dollar wise to get. I mean just the Kirins and Conjurants. As long as you have the other cards to support it already, there is nothing preventing you from spending like 0-5$ to get the cards and even if you just surprise your friends once with that combo and win the game its going to be worth it. However, with the soul sisters variant simply running good old armageddon would be more effective.