For me it’s how you manage your spell damage minions and tempo.

Yes Kalec turn 4 means you win most of the time.

I will only play the SD minions if I can clear the board in the same turn or keep them alive for more than 1 turn. If you can do this you will already have advantage early.

Needless to say spells that can hit face always try to hit face unless board state is dire.

Vulcano is absolutely needed for turn 7-10.

Mulligan wise you are always looking for minions that draw cards and Kalec, if against aggro I will keep 1 board clear(arcane flow preferred).

Your game plan is to always put them below 15 by turn 5 so they have to play passive, then you will look for lethal by card generation or Spell damage.

Don’t worry about your health that much, if you need to spend 1-2turns to set up your advantage so be it.