Garr

#1. Before the fight:

This fight is one of the longer fights in Molten Core, so you can make make great use of a pet toy here, such as [Ancient Cornerstone Grimoire] or [Arcanite Dragonling] or [Mithril Mechanical Dragonling], etc.
(Do NOT use [Gnomish Battle Chicken] as it is bugged in WoW: Classic.)
Take a look at your clear times. This fight may go long enough to use more than one explosive. If so, use your first one early to ensure you can get a second one off.

#2. During the fight:

Make sure your maintain high Slice and Dice uptime. That's it!