Titansteel Bar

Source

This item can be crafted using Mining (450); taught by Grand Master Mining trainers for 20. ~~Titansteel can only be smelted every 20 hours.~~

Materials required
	3x [Titanium Bar]			1x [Eternal Fire]
	1x [Eternal Earth]			1x [Eternal Shadow]

As an ingredient

This is used as the main ingredient for almost all of the high-level Blacksmithing epics, as well as some Engineering epics; including the Mechano-hog / [Mekgineer's Chopper].

Acquisition

It should be noted that Titansteel, as of Patch 3.3.3, no longer has a cooldown. (See Below)

The main bottleneck facing people who want to make high level or epic items is the 20 hour cooldown on the ability to smelt titansteel bars.

Several solutions exist for this.

Titansteel does not decay, so stockpiling it well in advance of any need works.
Titansteel can be purchased on the auction house.
One can use "use the cooldowns" of other people, be they friends or other players hired for the purpose.

A great place to acquire all the materials is in Wintergrasp. Elementals that often drop the crystallized elements of all varieties can be found there. If your faction controls the fortress, Revenants that drop the crystallized materials more reliably also appear. Circling the area with [Find Minerals] on should eventually yield enough titanium ore.

If one has access to a highly trained alchemist, the much easier to acquire saronite can be transmuted into titanium (without a cooldown).

The downside of searching in Wintergrasp is that if your faction is highly outnumbered, it can prove difficult to live long enough to mine these nodes.