The Iron Price

Upon entering the room where Gruul is, pan your camera towards the ceiling. In a small triangle formation around the center ring of the ceiling, there are three clickable ores. These are the Pristine True Iron Ores you need to collect for the achievement. Of course, they're all the way up there and we have no way of flying, so how do you get them?

Simple, get a lift from Gruul...specifically, his overhead smash ability. You have to have enough health or mitigation active to be hit head on by it and get knocked up into the air, just high enough to where you can click one of those ores to pick them up at the peak of your trajectory. They're far apart enough, however, that you'll need to do this three times separately over the course of the fight. Once all three have been grabbed from the ceiling after smash-jumps, you're free to kill the boss. Just make sure that whoever clicked on those ores stays alive to the end, that's likely part of the requirement (we didn't get a chance to actually test this as it was discovered during mythic testing).

Enjoy, achievement hunters~

Quick tips you may find useful:

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• As Lucivero said, we were misunderstanding how the knock-ups work. The farther, the higher.
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• Position the boss at the entrance, you can get two ores from there (the farthest ones). Move the boss to the opposite side for the third one. Don't move it too far though, or the boss will throw the player too fast and it will be harder to click on the ores.
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• Put a mark where your raid should stand before the [spell=155301] (it targets a random raid member) so the ability is casted just below an ore.
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• The ability has no specific timer and seems to share CD with [spell=155326] (so if the boss casts Petrifying, don't expect a Smash before the cleave). Stack when it's safe after [spell=155080], and move back to the two group positioning before the boss reaches 100 energy.
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• Fall damage can easily kill you, someone who can avoid or mitigate fall damage is more useful. If you are a mage, I found better to cast slow fall before the smash.
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I hope this helps ^^

Good luck with the achievement! :)

What is dead may never die.