Terros
Terros is the second boss in the Vault of the Incarnates. During this encounter Terros will always be in the center of the room and cannot be moved. Terros' key ability is a huge hit that needs to be soaked by the raid and spawns rock pillars that must be destroyed by the tank. Each time it reaches 100 energy, Terros will obliterate a quarter of the room, making it inaccessible and putting a time limit on the encounter.
Terros notably drops Terros's Captive Core which is needed for Iskaara Trader's Ottuk. Terros' regular loot has the following item levels: 376 (LFR), 389 (Normal), 402 (Heroic), 415 (Mythic).
Raid Positioning
Since Terros is stationary, tanks must always be in melee range to prevent Tectonic Barrage from casting.
Raid should be somewhat stacked, with ranged staying close to melee to make soaking Rock Blast easier.
Depending on which direction your raid chooses, the raid will move either clockwise or counterclockwise around the room after each cast of Resonating Annihilation.
Ranged and melee generally want to position near each other since most abilities are targeted on players locations.
Tactics
The current tank should always remain within melee range of the boss.
Raid stacks up in the same quadrant .. they can split slightly, ie, ranged behind melee, but don't spread sideways.
Rock blast (large yellow swirly with "flame") stack at least half the raid to soak damage.
Awakened earth leaves pillars - try to place them fairly close together.
Concussive slam will remove pillars.
Resonating annihilation targets one player, but will then cover one quarter of the room .. move to the next segment.
Shattering impact - large yellow circle - move away and then back to position.
Heroic
Fractured rubble .. rocks fall from the ceiling. Avoid.