When you fix the frost trap near his patrol route, he'll get frozen. If you gain the King of the Gordok buff from completing the Tribute Run, he will become friendly and offer the buff Slip'kik's Savvy: "Chance for a critical hit with a spell increased by 3%." for 2 hours. This now depends on the level of the player, since in Patch 2.1 the following change was made: "Fengus' Ferocity,Mol'dar's Moxie,Rallying Cry of the Dragonslayer, Slip'kik's Savvy and Spirit of Zandalar these buffs will no longer work on targets over level 63."
Slip'kik is still inside the ice block after you become King--amusingly, this does not prevent him from talking to you or buffing you.
See Dire Maul NPCs
Patches and hotfixes
Patch 1.3.0 (07-Mar-2005): Added