What Does Depleted Mean?
Normally if you play a power card three things happen: You gain one extra power to use this turn, you gain one extra maximum power, you gain any additional influence from the card. If the card is depleted then you still get the extra maximum power and any influence but not the point of power on this turn.
There are also ways of getting standard power sigils that are depleted. For example Forgotten Find allows you to play two power cards from your Void in depleted state. So your maximum power will go up by two ready for next turn, but you won't get any extra power this turn (if you did, Forgotten Find would pay for itself!).
Perhaps the most extreme example is A New Tomorrow that allows you to play 10 power cards from your deck in depleted state. An extra 10 power is a massive advantage - but you can't actually use it until the turn after you play A New Tomorrow.
This page written for Eternal version 1.22, Card Sets 1 & 2
Last updated: 8-08-2017