In reading practice the twentieth trump has a narrower and more distinctive sense than its keywords suggest.
The dominant reading is a summons: something that calls the querent to account, arrives from outside, and requires an answer that cannot be deferred indefinitely. The resurrection imagery supplies the specific flavour, which is that what is being called up is something the querent thought was finished and buried. Old matters returning for settlement is one of the card's most consistent practical meanings.
The second reading is judgement in the assessing sense: a period being weighed, a decision made about the querent by someone else, or the querent's own reckoning with what they have done. Readers differ on whether this is threatening. The card's own imagery is not, the figures rise gladly, and most practice follows the image rather than the word.
A third reading is vocation, in the literal sense of being called to something. This is common in psychological and spiritual practice and follows Crowley's Aeon more than Waite's Judgement.
Waite gives weakness, indecision and a decision deferred for the reversed card, which is a genuinely different meaning rather than a negation: not a summons cancelled but a summons unanswered. Readers who do not turn cards find the same reading in an upright Judgement surrounded by cards of stasis. It is one of the clearer cases where the two schools describe the same thing by different routes.
Whichever reading is taken, the card assumes something has already happened. It is not a card of beginnings, and a reader who treats it as one will usually find the querent nodding politely at a description of a situation they left behind some time ago.