The goal is to Invoke 4 times and draw a lot ASAP
You will gain tempo with the invoke effect very well, and you can use the imps and lackeys as sacrifices for more cards and lackeys
you probably don't tap a lot though, you will mainly tempo most of the times anyway by drawing cards from
Veiled Worshipper, Kronx Dragonhoof and Mortal Coil

Expired Merchant is for Kronx Dragonhoof, Galakrond, the Wretched or Zzeraku the Warped, or in emergency Crazed Netherwing.

Zzeraku the Warped can be played at turn 8 for immediate pressure, a second one is good for even more pressure

once you have two Kronx Dragonhoof you can just go nuts with the Galakrond

If you managed to get 2 or more galakronds you are in a very good position, and they don't lose upgrades after being discarded.

you can kill the Expired Merchant with Mortal Coil, EVIL Genius or anything that kills the merchant

I have added Nether Breath and Dragonblight Cultist to deal with the board much better once you have a dragon in hand so even if you have Zzeraku the Warped in mulligan hand these two cards can help you a lot once you get them in hand.

Hellfire and Crazed Netherwing are for board clearing, can be combined with other minions from hand too for the best board clear outcome, just be sure to hold a dragon when you play Crazed Netherwing which can be gained by lackey too Draconic Lackey.