Why does this MetaBattle Rotation work?
With the rotation you still have a 100% upkeep on the boons from the facets, but with the addition of Quickness from Impossible Odds.
Surrender and serve me in life, or die and slave for me in death.
So the rotation on metabattle is trying to maximize personal DPS, which means keeping you in Shiro for Impossible Odds as much as possible. In that case, you pre-buff in Glint, break Facet of Nature for the burst of boons before you engage, then swap to Shiro for a big burst of up front damage.
In general you’re swapping between two modes, buffing/support mode and DPS mode. Since you reset to 50% energy every time you swap legends, you have an incentive to constantly run a deficit to take advantage of that energy spike. So in the base case, you turn on all the facets (realistically, almost all the facets) until you run out of energy (at which point they all turn off on their own, without going on a long cooldown – this matters if you’re using Facet of Nature to boost boon duration), then you swap to Shiro, use IO to drain all your energy, then swap back to Glint and turn your facets back on. This maximizes your raw output; you get more ‘stuff’ done to brute force down encounters.
Between the 50% boon duration from Facet of Nature and the 15% built in from Herald, if you swap legends every 10 seconds you’ll maintain 100% uptime on any critical boons. The trick is that facets give their boons immediately after activation and every 3s thereafter; it doesn’t matter if you swap prematurely. So if you turn on Facet of Nature, Darkness, and Chaos immediately after swapping to Glint, you’ll get 4 ticks before you can swap again – at 0, 3, 6, and 9 seconds. That gives 12*1.65 = 19.8 seconds of uptime, which basically covers a full cycle. Those 3 also put you at -4 pips, so throw in a couple Precision Strikes and Facet of Elements actives and you’ll drain your energy in roughly 10 seconds.
You then have cover to swap to Shiro, IO with all those buffs still up on your party, expiring just as the cooldown to swap back is up. Repeat.
That’s the default pattern, perfectly good for relatively easy content where you just want to maximize damage output. There are a couple more patterns that matter. First, sometimes you want to just sit in Glint and maintain fewer facets. Good reasons include clearing trash where it’s honestly not worth the effort to go full bore, or when fighting encounters with critical breakbars / big CCs. You’d want to hold energy back so that you can Surge of the Mists on demand, for instance, or have the swap available so you can quickly break CC (such as the really long fears from Tequatl or Sloth). In those cases you’d maintain less facets, just 2-3, to keep your energy and cooldowns up so you can use them reactively instead of dumping it all proactively.
The other is the raid, 100% Facet of Nature uptime pattern where you put more emphasis on the support you can put out. Here you usually drop Shiro for Jalis or Mallyx, since you can’t use IO with Facet of Nature up. Here there’s less pressure to swap as quickly as possible, and more emphasis on not ever letting your energy hit 0. Here I’ll be more tactical about which facets I turn on in Glint – more if I know I can burn down my energy quickly since I just finished a CC phase, fewer if I know one is coming up soon – and burn through Jalis or Mallyx pretty quickly so I can get back into Glint.
This isn’t really a matter of ‘pick one and stick to it’, but understanding that you can use these tools in different ways to different ends, and adjusting what you’re doing in accordance with the demands of the encounter.