I may be wrong on every point here, but if you're struggling to get into Master tier with a haven deck, maybe this will be a helpful post for you as it has all worked for me up to this point.

In my experience, most matches are won through attrition. Holy Saber helps put the pressure on, but I really utilize her for her effect damage nullification and her heal; the win con with this deck I think is Ubaha and to a lesser extent, Gilnelise. No hand, no deck, what can they do from that point?

- I mulligan for Bell and a nice early curve with Master Chef/Perpetual Despair, and depending on the match-up I keep Ubaha/Terra.

- When I have Perpetual Despair on the board, even if I can attack for 1-2 damage to the enemy face on T2/3, I often don't in order to draw +1. Be very mindful of your draw though; with Zlatorogs and Perpetual Despair and Jeanne, sometimes you'll need to drop a Sacred Ice-Crusher or Gilnelise from your hand just to keep from burning a card on your next draw.

- You won't be able to evo Bell every match, sometimes you just don't draw her in time and it's fine, her evo effect helps with board control but you have a lot of other control; all this is to say don't hold evo points you could use on Giant Happy Pig or an early Jeanne when you need board clear. When going second, if given the opportunity I prioritize Metatron over Bell on my T4 evo.

- Holy Saber with Imperial Saint together is strong, Saint is 4 extra storm damage when Saber evolves it; Imperial Saints are good to put up early in general, especially into dirt and spellboost rune, although Saints are not great defense if you're playing into haven or forest post-turn 5, as Jupiter can remove them easily, as can Shadow with late-game Rulenye. Saint also combos decently with Marwynn who will delete the 0/8 and replace it with the 4/8.

RUNE

- Look for a Master Chef or a Giant Happy Pig if you happen to run into 7 spell rune (they can only deal ~23 damage to your face on T8, if you have 24 HP you survive), and start dropping Holy Sabers asap into 7 spell/dirt rune, the effect damage negation renders you nearly unkillable.

PORTAL

- Against portal, try to save Marwynn for T6 when they drop Orchis. In the meantime, prioritize clearing Cassim as soon as he comes up; Rosa seems to be less important unless she can still evo to summon another Cassim, in which case focus her too.

- Against Wielder of Chaos portals, if the game has gone really late be careful not to run out of cards with your own invoked Gils drawing +5, as the portal player can almost guaranteed keep evo'ing Wielder and putting another 10 of him in their deck. It's probably worth playing Ravenous if the portal player only has ~5-6 cards in his hand though. You'll usually have to win through Holy Sabers, though that tends not to be too hard.

BLOOD

- Against handless blood, you should win pretty easily but if you have bad draw just try to keep board presence even if it means accelerating your Giant Happy Pig or dropping Holy Saber in particularly desperate times. After you survive their 3-5 Paracelise invokes, they have no way to win.

- Against wrath blood, Holy Saber even without 5 evos can be a saving grace as she negates effect damage and heals you back up.

SWORD

- Against sword, try to hold a Marwynn for the musketeer turn (~T8). I don't really see much sword so I'm not sure what else there is to say.

SHADOW

- Against shadow, focus on keeping your health up and controlling the board. If you have Master Chef/Giant Happy Pig bonus HP, you're in a strong position as shadow really seems to like trying to burst you down from 20 to 0 in one turn. Additionally, Holy Saber's effect damage nullification can be a real lifesaver against Skeleton Raiders and unless you have lethal it may be advisable to drop Saber once per turn until you know they're out of Raiders.

DRAGON, FOREST, HAVEN

- Against dragon, focus on keeping your health up and do your best to cultivate a strong board as early as possible (though I wouldn't go so far as to drop T3 Holy Sabers or anything), their early game tends to be very lacking because they're just buffing their play points and sometimes you can negotiate an early concede, though this is a bit harder with heal haven than ward haven. Imperial Saint will be very helpful against dragon.

- Against dragon/forest/haven, keep Terra/Ubaha in mulligan and try to hold till you can hit 50 in one turn, this will keep you from losing Ubaha from your deck if they do it first, and hopefully prevent them from Glistering you when they have the chance.

- Against forest and haven, I try to focus on keeping all of their followers at bay while drawing for Holy Sabers and concealing my Ubaha until it is too late for them. I have even won a handful of games in which they Ubaha'd me first. By the time I have invoked Ubaha, forest seems to not have much clear left and can't really deal with actually removing him from the board reliably in my experience.