mulligan for 2 mana Wposts > Insight = Draconic Studies > Circus Amalgam ( always take it if you have draconic studies already) > Palm Reading (good with insight on hand) > lastly if you have both Xyrella and desperate prayer in mulligan against anything else than rogue then keep it.
early game is all about placing watchposts and low cost dragons/amalgams. Against most classes its best to coint out the 2 mana Watchpost on turn 1 if you can. That way you will get at least 2 turns with it sticking (or one with them wasting removals). If you have draconic at hand then try to find low mana minions. At this stage Amalgam> any low cost dragon. Try to corrupt insights.
Mid game is about getting a bit ahead of your oponent. Try and keep stuff alive on your board and clear theirs with Xyrella + healing and Samuro + Apo / discovered buffs and hysteria. Your best clear is Soul Mirror, if possible try to get some nice minion tags for your N'zoth (avoid small minions with tags when using it). Play your big dragons if they are discounted.
Late game is all about closing it out. You have two board fills with Kargal and N'zoth. The second is bonkers with the new elemental. The good thing is that since you played a lot of minions thruought your game the opponent is mostly out of removal at the end thus your big board filling turns will be better as they will be struggling to get rid of it.
Ive played this deck thru whole silver and gold ranks and it worked great.
Mages (deck of skillz) -This fight is in favor for us. If they dont highroll for first 3-4 turns straight then its GG for them. Need to lookout for devolving missles. You dont want to get your elementals devolved! Most fights they are struggling whole game to keep your board clear and fail to do so by the mid/end game. Its good to use Nameless One on their Solarian if they play it. If they highroll from turn 2 to turn 5 then you cant do anything about it. It happens 1 in 10 games tho.
Paladins (secret)- is more even. Again if they dont highroll first few turns then its an even fight. Try to bait their secrets at worst time for them and discover PW: Death for their healing 8/8 guys. The rest is the same, play for tempo and make good trades.
Rogues (weapon rog.) you need healing here and if have it then they lose. 2 mana and 4 mana watchposts are crazy good on this matchup
Tiktakus Lock is the worst matchup. Can be won but only if you get really good curve plays and they dont burn your N'zoth and Kargal. Need to bait out both 8 mana hard removals.
The rest (not many other decks out there) is kind of same tempo style play.
Possible card changes:
Samuro + Apo for 2x beasts of some kind - best bet is the 3 mana scorpids that discover spells.
Deperate Prayer x2 for Raise Dead x2 - the DP gives much more consistency to your Xyrella and overall heals. Its a good card. But to each their own i guess