Hearthpwn

For the Mulligan it is quite situational, I won't got through every card but for the basics:

Dragon Synergy - do I have Wyrmrest Agent/Twilight Whelp/Blackwing Technician? mulligan rest away pray for dragon

injured synergy - normally I will only keep Injured Blademaster with The Coin or if I draw Circle of Healing.

Try to preplan your first turns - if you are against shaman Lightning Bolt, Spirit Claws and Totem Golem are likely - dragon synergy & Northshire Cleric to hold card advantage in early turns once Totem Golem is out of the way you are usually in the clear till pressure comes back in around turn 5/6

vs hunter - Secretkeeper, Huffer, Eaglehorn Bow, Freezing Trap - no ping so Injured Kvaldir works best here aim for Injured Kvaldir & Circle of Healing

warrior - Fiery War Axe, Ravaging Ghoul, Blood To Ichor, Alexstrasza's Champion - dragon synergy tends to be best here Wyrmrest Agent power word shield if draw early

Zoo Lock - Malchezaar's Imp, Flame Imp, Dark Peddler - dragon synergy is best here ideally with The Coin Shattered Sun Cleric on 2 or played on 3 to deal with Silverware Golem/Malchezaar's Imp and a Holy Nova around the midgame will seal the match

Leave a comment if you want to know any other mulligans/strats. cheers!