Spirit Phase

With Spirits that get to choose multiple Growth options, if more than one option has "Gain Power Card", can I gain a Power Card *then* pick which Growth choice I was using?
No. You choose a set of things to do, then do them all. If you have multiple Growth choices, you then do this again, and cannot choose one you already picked this turn.
(Discussion elsewhere)  Tags: Growth, Keeper of the Forbidden Wilds, Sharp Fangs behind the Leaves, Starlight Seeks Its Form, 0 more...

With Spirits that choose more than 1 Growth option, can I see the results of one choice before picking the next?
Yes — you can completely finish resolving your first Growth choice before making your second choice.
(Discussion elsewhere)  Tags: Growth, Sharp Fangs behind the Leaves, Keeper of the Forbidden Wilds, Serpent Slumbering Beneath the Island, 3 more...

If you have a Growth option which lets place two Presence, can you chain them, placing the second one within range of the first one?
Yes, you can do this. In general, after you choose a Growth option, you do everything under that option, in any order you wish. (p. 8)
(Discussion elsewhere)  Tags: Presence, Growth, Thunderspeaker, Lightning's Swift Strike, 1 more...

Can I wait for the results of another Spirit's Growth before making my own Growth choice? E.g., see if they draw into a Power Card which handles a bad situation before making my own choices?
Yes.

The only rules constraints are that each individual Spirit must Grow / Gain Energy / Play Power Cards in that order, and that all Spirits must complete the Spirit Phase before anyone starts resolving Fast Powers. [p. 8] Other than that, players play simultaneously and may confer as they wish, so for instance, one Spirit could plan out their whole turn before another decides which Growth they're taking, or two Spirits gaining Power Cards could base their decisions on what to keep based on each others' draws. How lenient you are about individual Spirits rewinding - eg, going back to choose a different Growth option - is ultimately a playgroup decision, but most people seem to be fine with it so long as you're not rewinding "gain a Power Card".

In some cases outside of the core game, a Spirit's Growth may even change the board - waiting for this is also fine. (E.g., Keeper of the Forbidden Wilds could push Dahan by making a Sacred Site, changing what lands Thunderspeaker could add Presence to.)
(Discussion elsewhere)  Tags: Growth, Timing, Gaining Power Cards, Keeper of the Forbidden Wilds, 1 more...

With the growth of A Spread of Rampant Green, can I gain a power card and then choose where to use the first (non-optional) growth option?
Yes, you can choose where to place your Jungle/Wetlands presence based on a power card you gain that turn.

This is more explicit in the Branch & Claw rulebook, where there are more spirits with multiple growth choices.
(Discussion elsewhere)  Tags: Growth, Ordering, A Spread of Rampant Green, Relentless Gaze of the Sun, 0 more...

What happens if Serpent Slumbering Beneath the Island is at its Presence limit and attempts to add Presence?
It cannot add more Presence, by its special rule, so nothing happens. (True for both Growth and Presence-adding Powers.)

It may choose to instead reposition a Presence already on the island (sidebar, p. 14).
(Discussion elsewhere)  Tags: Growth, Serpent Slumbering Beneath the Island, Unrelenting Growth, Gift of Proliferation (A Spread of Rampant Green), 0 more...

Can you use a Presence track action in the middle of Growth?
Yes, so long it's in between actions (or before choosing a Growth option). Generally, each icon is one Action(†).

For instance, Downpour Drenches the World could choose its second growth option (which has 2 "Add a Presence" icons), add 1 Presence to uncover a "Move Presence 1" space, use the Move 1 to shift a Presence, then place a second Presence from the new position. Or Many Minds Move as One could gain Energy with its 3rd Growth option, then use it to gain a Power Card before deciding where to place Presence.

(†) = With an exception for icons that explicitly indicate "do this thing multiple times", like Fractured Days' "xN"s or Ocean's "....to/from EACH Ocean".
(Discussion elsewhere)  Tags: Growth, Presence track, Actions, Downpour Drenches the World, 2 more...

When your Presence track gives you "Any" element, when do you have to choose what element that is? Can you change what it is during the turn?
You can wait until the middle of your turn to choose what it is, but once you've set it for a turn, it can't change that turn [base rulebook p. 14, last item under Presence Tracks]

This holds true even if you're restricted on which Elements you can choose (e.g., Wounded Waters Bleeding having a "Water / Animal" space instead of a full "Any"). [Nature Incarnate rulebook p. 9]

This contrasts with the timing of choosing flexible Elements gained from different sources.
(Discussion elsewhere)  Tags: Elements, "Any" element, Timing, Bringer of Dreams and Nightmares, 10 more...

How does one move Presence during Growth?
When a Growth choice says "Move Presence" (with a curved arrow), move one of your Presence up to the shown number of lands away from where it currently lies. When the Growth option says "Add Presence", but instead of adding from your Presence track you choose to add one already on the board (per the p. 14 sidebar), you can take it from anywhere. (This is still considered "adding a Presence", not "moving a Presence"; later reprints of the rulebook use the term repositioning.)

Ocean's Hungry Grasp also has Growth choices with "Push Presence" and "Gather Presence"; these work just as Gather and Push usually do (to/from an adjacent land). They are mandatory.
(Discussion elsewhere)  Tags: Growth, Presence, Ocean's Hungry Grasp, Serpent Slumbering Beneath the Island, 0 more...

Can you use Energy you gain during the Fast Power Phase <i>(e.g., from Boon of Vigor)</i> to pay for cards you play that turn?
No, you cannot. You need to pay for all Powers when you play them, during the 'Play and pay for Power Cards' part of the Spirit Phase at the beginning of the turn. The Spirit Phase needs to be entirely completed before you start the Fast Power Phase, when you would gain the energy from cards like Boon of Vigor.

Typically the Energy you gain from powers like this will only be useful on the following turn, unless something makes you use Energy in the middle of the turn.
(Discussion elsewhere)  Tags: Energy, Playing Power Cards, Boon of Vigor (River Surges in Sunlight)

Do I have to do everything shown in a Growth option I pick?
Yes. You can do them in any order, but must do everything shown if possible.

Usually, there's no downside: Reclaiming, gaining Energy/Power Cards, and adding Presence are strictly good. (You can always move a Presence already on the island when adding Presence [p. 14], so "running out" isn't a concern.) Spirits with "Move a Presence up to Range N" Growth effects can Move it 0. However, a few Spirits do include things you'll have to work around - eg:

If you can't do something in a Growth option, you do as much as you can and skip the rest. (Eg: if you're supposed to Push Presence from each Ocean, and there's a board where none of your Presence is in the Ocean, you don't Push on that board.)

When you reposition Presence on the board rather than adding new Presence, where can you measure the range from?
You can measure the range from any Presence, including the one you are about to reposition.

The sequence of events for adding Presence during growth, you

Normally this is picked up from your Presence track, but you can pick it up from anywhere on the island instead if you want. The sequence is similar when a Power lets you add Presence.
(Discussion elsewhere)  Tags: Growth, Repositioning Presence, Presence, Gift of Proliferation (A Spread of Rampant Green), 3 more...