Depending on the Power and Incarna in question, this may be weaker than when used by the original Spirit. For example, while Frightful Keening can still push the Incarna of Wandering Voice Keens Delirium, and still generates Fear if pushing into a land with Invaders, only Wandering Voice Keens Delirium can use this Power to add Strife via Keening Spurs Grievances. Tags: Transferring Power Cards, Incarna, Entwined Power, Blazing Intimidation (Ember-Eyed Behemoth), 7 more...
Absorb Essence effectively becomes "Gain 3 Energy. Target Spirit gains Any Element and 1 Energy." (You cannot follow the instruction "Move 1 of target Spirit's Presence to your 'Deep Slumber' track", because you do not have a Deep Slumber track.)
Ocean's Special Rules define what "Drown" means: "Destroy Drowned pieces, placing Drowned Invaders here [on Ocean's playmat]." So if another Spirit Drowns an Invader, it is Destroyed (by that Spirit), then goes onto Ocean's playmat. Similarly, since Terror Stalks the Land defines what "Abduct" means, abducted pieces go to The Endless Dark whether or not Breath of Darkness Down Your Spine is the one using the Power.
If the effects of the special rule didn't have anything to do with targeting the Power, it might be more ambiguous (since Entwined Power is only supposed to affect targeting), but Mists Shift and Flow is very explicit that it can be used to target Powers. Tags: Targeting, Move, Shroud of Silent Mist, Mists Shift and Flow (Shroud of Silent Mist), 2 more...
For instance, Gift of Living Energy (a Minor Power) wouldn't count it towards "If you have at least 2 Sacred Sites...", nor would Fear of the Unseen (a Fear Card) treat it as a Sacred Site for scaring away Invaders.
Note that if you Entwine with River Surges in Sunlight, their River's Domain Special Rule only applies to them (read it as "counts as your Sacred Site"). So for targeting, they would treat any Wetland where either of you have Presence as a Sacred Site, but you would still need 2+ Presence as usual. Tags: Sacred Sites, Presence, Entwined Power, River's Domain (River Surges in Sunlight), 6 more...
How does Entwined Power work in Destiny Unfolds?
If Target Spirit still has cards in their Destiny, they gain one of them and you gain another one if any remain. (If there was only one card in their Destiny, you won't get a card.)
If their Destiny was already empty before resolving Entwined Power, resolve it like normal.
To expand on the situation, a land contains one Presence from Rising Heat of Stone and Sand, one Presence from another Spirit, and a Town with 1 Damage. "Entwined Power" is used between the two Spirits, and then Rising Heat uses a Power that requires a Sacred Site there for targeting. Even though targeting the Power is legal by "Entwined Power," the land only counts as a Sacred Site for Targeting, not for the Special Rule "Blistering Heat." Tags: Counts As, Rising Heat of Stone and Sand, Blistering Heat (Rising Heat of Stone and Sand), Entwined Power, 0 more...