WHM T13 Questions

[Sleigh]

Gigaflare, you can M2 between the wyvern spawning and the damage coming out pretty easily if you time it. Nothing more is needed typically if MNK Mantra'd.
Megaflare > Rage, you can M2 the Megaflare and then do any required healing to get people up for Rage, and that will cover a lot of what the Rage will do.
51% Gigaflare, M2 > C3 after you're stacked in the middle. I find doing C3 > M2 is worse due to people not staying stacked at that point on average, and you'll be full HP by Megaflare anyway. If your SCH is for some reason using Eos and is going to WD at this point, you can skip the C3.

You can M2 immediately after Rage but that can be a ticket to death occasionally. Usually works out, but it's an avoidable risk with very little benefit to do it in that time frame so I always pre-M2 or M2 after the wyvern is dead.