Turn 7 Mecha'thun Warlock

Drawing cards with the Rod equipped makes drawing more cards cheaper, etc. This cost reduction hits a critical mass around turns 6-7 and you can manually draw your entire deck and OTK - without having paid mana for removal or healing.

To give an idea of how powerful the Rods are, all cards in the deck combined cost a grand total of 64 mana to play. This deck ends up playing almost every card for a total of 28 mana or less. That's around 36 mana cheated by turn 7.

Soul Fragments make the Rods tick faster as well as make up the bulk of the healing.

Hoard Pillagers give extra Rods.

The combo is Vol'jin on some friendly minion to pull Mecha'thun, and then Cataclysm for lethal. Alternatively, you might be able to hard-cast Mecha'thun into Cataclysm if the cost reductions line up.

Always mulligan for Rods and one Backfire.

Try to prioritize card draw and equipping Rods over minor removal - you'll end up able to play more removal and more healing for less mana.