This is the deck I am experimenting with and it’s been very strong in diamond (70% percent winrate but I only played like 8-9 games).
Here are my reasoning for running some of the unpopular/underplayed cards:
Vespyric Call - It’s technically a 0 mana spell which adds a Vesypr with a +1/+1 buff to your hand. Only reason the card isn’t broken because some Vespyrs aren’t great but most of them are so it’s worth the risk.
Bonechill Barrier - Combos well with Glacial, Planar Scout on T1, Mirkblood. It the limits enemy’s movement and forces them to spend resources to remove it. All around a great card.
Avalanche - No one ever plays around it. You don’t get to use it very often but when you do you win the game on spot. Such a crazy effect.
Planar Scout - Very strong card due to it’s ability to deny the middle mana tile when going first. It’s even better when you get to play something else on the same turn but denying the tile is usually good enough.
Prophet - Self explanitory. It protects your minions and face from spell damage which is fairly common in this meta. Definitely worth the investment of 1 mana.
Fenrir - 3 mana 6/4. A nobrainer.
Mirkblood - Another great all around card. It just need to live to provide lots of value in form of stats. Stats create tempo and playing the tempo game results in a sure victory. It’s also good when you get to combo it with other minions from hand.
Nightwatcher - I used to run Sunsteels instead but I switched them for Nightwatchers upon realizing they’re better in every way. Like Sunsteels, they are very annoying to remove but they also have a big upside in form of making cards like Spectral Revenant and Makantor useless.
White Widow - The card is surprisingly good on it’s own without any additional synergy. I urge you to try it for yourself in any tempo deck really.
Hollow - Very important to have it in order to counter Ironcliffes which are very common nowadays. I’m considering replacing Tracer for a second one but I’m not entirely sure as I value the mobility Tracer gives me a lot.
Pandora/Nemesis - They serve the same role of being late game minions that close out the game, pretty straight forward I also considered Exun but I’m not sure which one of the two to replace for it.
Feel free to ask any questions and I’ll do my best to answer them!