Sly

It looks like you'll need Kyrian Assaults active for 3x times to finish this achievement and get [npc=179083]. With the 3.5 day rotation of 4 covenants' assaults, this will take at least 28 days to complete and (based on the first Kyrian Assault post-release) up to 6 weeks into Chains of Domination if you don't miss a single opportunity to find Sly.

TomTom:
/way #1543 42.13 44.48 Orator Kloe
/way #1543 40.71 51.58 Sly#1
/way #1543 38.03 39.73 Sly#2
/way #1543 32.89 44.19 Sly#3

• When you achieve A Sly Fox with the third successful rescue, [item=186539] will be delivered to your mailbox.
  
• The hidden quests that mark the completion of one rescue of Sly don't reset. ([quest=64024], [quest=64022], [quest=64023])
  
• Another hidden quest is obviously there to make sure that players can't speed up the process because it's flagged completed for the span of a whole Kyrian Assault if you were interacting with Sly. ([quest=64019])
  

  /run for k,v in pairs({SlyHuntActualAssault=64019,Sly1=64024,Sly2=64022,Sly3=64023}) do print(format("%s: %s", k, C_QuestLog.IsQuestFlaggedCompleted(v) and "\124cFFFF0000Completed\124r" or "\124cFF00FF00Not completed yet\124r")) end

  
  
• Tracking down Sly is character-specific, other characters can't circumvent the one rescue per assault limitation. (not sure if doing it multiple times makes any sense, usually achievement pets are limited to 1 per account)