https://querki.net/u/darker/spirit-island-faq/#!.3y28aqg
https://querki.net/u/darker/spirit-island-faq/#!.3y28aqg
As I understand it, a Range-extending power just adds its buff to the Range of any power...so to use Reaching Grasp as an example, if this power is used on you you just add +2 to the Range number in all powers you're using that turn. So "Punish Those Who Trespass" would go from Range 0 to Range 2 because Reaching Grasp lets you increase that number. The Threshold of that power which specifies that you can instead apply the effects across "lands in which you have Presence" would not be affected by Reaching Grasp because it only looks at the "Range" box of a power, it doesn't care about the Power's actual text. It would be the same with Mantle of Dread, one of Shadow's cards which has no Range specification because it targets a spirit - the text specifies that that spirit can Push one Explorer and one Town from one of their lands. This can't benefit from something like Reaching Grasp because it's the power's effet text, not the Range.
Spirits like Ocean and Wildfire love powers like Reaching Grasp because it lets you stretch across and use your Range 0 Innates to nom/burninate stuff >:).