The Anger card, Emotions family, yang polarity, indicates an energy seeking to free itself from a constraint. It signals a boundary that has been crossed and needs to be acknowledged. Drawing this card invites you to use this force to assert a limit rather than simply endure it.
In Oradia's mirror-card system, Anger answers to Powerlessness: the two don't oppose each other, they answer each other, like two sides of the same movement.
This page gives the card's general meaning. In a real draw, the Anger card is always read in relation to the other cards drawn and the intention set at the start — it's that combined reading, unique to each draw, that the online oracle develops.