This is a Praxis sentinels deck I've been working on for a while. This deck can be tricky to play because so many of the cards reward you for playing other cards after them. You're always giving up some kind of value no matter what. For example if you play Powercell before Flameheart Patroller then you get an extra attack permanently but miss out on damage from Flameheart. Think ahead about how long you want the game to go and what resources will matter. This deck can play a long game and win out of nowhere with Technique plus Blast (sometimes even on Groundbreaker).
There are a few notable inclusions/exclusions.
Pyroknight: this idea is from Zac Hill (zdch). You want aggressive early plays that scale into the late game. This does exactly that and has a threat of activation where if they don't kill it your 1 drop becomes huge and if they do you slam an Opum.
Autotread: this card didn't do enough. You're not fast enough to want to go all in and you need to hit power drops so discarding is always rough. It was nice as a 1 drop sentinel to enable things but Copper Conduit can fill that role if need be.
Barricade Basher: same rationale as Autotread. Discarding is rough. A 5/5 for 3 isn't worth going down a card.
Redplate Crasher: I was torn between Groundbreaker main and this market until zdch said he had this main and Breaker market. After trying this main I feel this configuration is right. It single-handedly bonds out Tempered Sentinel and can push Pyroknight through most blockers.
Moonstone Vanguard: This allows you to run more power without flooding. I don't run more because the deck doesn't want too many 5 drops and Opum is clearly better. Basically always pledge this on turn 1.
Fire Etchings: another suggestion from zdch. This deck wants to hit power drops. Similar to Vanguard Etchings is power that does something else in the late game. Don't be afraid to play this for power early when you have a spare power. With 8 market cards you'll likely draw another.
Power Base: Patroller likes dual power and Etchings likes Symbol. I'm only playing 2 Praxis Vow because I don't want Seat to be depleted. I believe 14 T sources is enough but could maybe see adding back 1 more Vow over a Fire Sigil.
Market: Standard is an amazing market card. It's power when you need it and a trick when you don't. Begin Anew was another suggestion from zdch. It's a nice way to refill your hand in grindy matchups. I like Ruin over Slag because the mirror isn't that common and being able to kill Perma on 4 power with Merchant is a big deal.