A lava wave will always start at either the north or south side of the island, then sweep across the island to the opposite side. All lava waves originating from the same side will always have the same configuration of gaps. If coming from the north, there will be a gap in the centre of the island, while if coming from the south, there will be gaps in the east and west ends of the island.
Just observing one side when Raid Warning calls out "The lava surrounding Sartharion churns!" is enough to tell where you need to be. Guild convention states that Sartharion be tanked at the south-east corner of the island, thus it will be easiest to turn towards the southern side when needed. There are two courses of action which you will need to choose between:
- If you see the lava wave's originating there (at the southern end), you need to be at either end of the island. As Sartharion occupies a large portion of the eastern end, the tank should stay in the eastern gap and the rest should be in the western gap. Of course, in this case, you will easily be able to judge where you need to go since you are observing the lava wave directly.
- If you don't see the lava wave's originating there (instead originating at the northern end), the tank should hop onto one of the "stepping stone" islands (off the main island) and the rest of the raid should be in the centre of the main island. However, during any drake phases, the raid may find that the (stagnant) lava off the west end is closer than the centre of the island. Do not be afraid to jump in; it is only slightly over lukewarm.
