Shattered (25 player)

Ignis will fire Scorch occasionally. This spell does Fire damage over time and leaves fire on the ground, which damages players and causes Iron Constructs to Heat up.After gaining 10 stacks of Heat, they become Molten. Bringing a Molten Iron Construct to one of the water pools in the room will cause them to explode.

Just offtank 2 of the Molten Iron Constructs until they become Molten and then bring them to a pool at the same time. You could use 2 OTs to make sure the Constructs don't run loose if one of the OTs is throw in the Slag Pot.

The Iron Constructs adds can gain the buff Heat by standing in the fire left by Ignis' Scorch.
Once Heat reaches 20 stacks, the Constructs gain the buff Molten, which lasts for 20 seconds.
If within this time frame they are kited to a pool of water they will loose the Molten buff and instead become Brittle for 15 seconds.
A single blow dealing 5000 or more damage to a Brittle Construct will shatter it, causing an explosion. Doing this last step to 2 or more Constructs within a 5 second window will grant this achievement.

The Constructs each give Ignis a stacking Strength of the Creator buff, increasing his damage by +15% per stack. Three of these buffs tends to increase Ignis' damage output to levels above the effective health of your average tank. As a result, the Constructs should usually be killed as soon as possible. For this achievements, two will have to be alive at the same time, putting strain on the tanks and healers and limiting the amount of time available to execute this achievement.

Tracking the achievement will not give you a timer. The achievement is awarded upon killing the boss, rather than upon killing the 2 constructs within 5 seconds of each other. This is due to the way the achievement is worded..