Originally posted by Dr. Snorbulizer:

Whats the easiest way to get a surtling core thingy?
Do I need just one to set up a smelter?

You need 5 for 1 smelter and 5 for 1 coal kiln. Be aware there are other uses for cores too such as portals, warding stones, and later game crafting stations too (plains level).

Surtling cores are found in crypts in the black forest (skeletons and ghosts are in them.. beware the poison skels as they can be hard to handle for your level of play).

However, crypts to not always have alot or cores. It is random how many are there but usually it averages to 2-4 but can be more or less. Its RNG.

Later after you defeat the second boss and enter the swamp, surtlings spawn at fire spouts in the swamp. Digging around fire and making it water only means that when surtlings spawn, they almost instantly die. When they die they leave surtling cores, coal and sometimes surtling trophies. The surtling spawns will eventually be the easiest method to get cores.

So the easiest is relative to your game play situation. At the moment it just means delving into the crypts carefully for your level. Good hunting.