Mulligans
General Mulligans
Always keep Reno and Doomsayer, keep Hellfire against board flood, look for 4 drops/ proactive plays versus control (Cairne, Mountain Giant, Twilight Drake, Refreshment Vendor).
Ultra greedy N’Zoth Renolock running the Youthful Brewmaster + N'Zoth, The Corruptor combo, as well as the Leeroy Jenkins, Faceless Manipulator, and Power Overwhelming combo.
Tips:
Saving Sunfury Protector and Defender of Argus for after Lord Jaraxxus comes down can increase your chances of surviving burst greatly.
Saving Brann Bronzebeard to double up on our limited sources of healing is generally a good idea vs aggro.
Dark Peddler should be held onto until he can be played with Brann Bronzebeard against control.
Power Overwhelming can be used in many ways in this deck. Power Overwhelming is mainly used for burst with Leeroy Jenkins but also can be used with Shadowflame, and Sylvanas Windrunner.
Overall your game plan is to cycle and be proactive against control, dig for win conditions and enable them with Emperor Thaurissan. My version runs 3 win conditions against control (Faceless Manipulator + Leeroy Jenkins, N'Zoth, The Corruptor with or without Youthful Brewmaster, and Lord Jaraxxus) as I believe this deck is should only be played seriously in a control meta. If you are looking to play N’Zoth Reno on ladder in a non-control heavy meta I would recommend Fr0zen’s list.
Always save Acidic Swamp Ooze for Gorehowl versus Control Warrior.
Against aggro your goal is to live until Reno Jackson is drawn so you can get value from your expensive cards. Getting off strong a Doomsayer, Defender of Argus, or Sunfury Protector can also win you the game versus aggro.
Using Emperor Thaurissan : Against control you should know what combos you will need so you should only play him once you can get adequate discounts. For example against a priest you would prioritize your Leeroy Jenkins combo over N'Zoth, The Corruptor as priest is weak to the burst. On the other hand discounting Youthful Brewmaster, and N'Zoth, The Corruptor is key versus Control Warriors who are more resilient to burst but less to high value minions like Cairne Bloodhoof. However, in almost all control match ups, discounting Lord Jaraxxus is a good idea so you can hero power the same turn as he is played. Against aggro play Emperor Thaurissan whenever you can get away with it as its one of the few ways you can out-tempo aggro.