Holding priority, cast Dualcaster Mage by paying its mana cost.
When Dualcaster Mage enters, it triggers, copying Return to Action, with the copy targeting Dualcaster Mage.
Resolve the copy of Return to Action.
Holding priority, activate Woe Strider by sacrificing Dualcaster Mage.
When Dualcaster Mage dies, it triggers, returning it from your graveyard to the battlefield.
Repeat from step 3.
Resolve all Woe Strider abilities from step 5.
This clever loop turns Dualcaster Mage into an endlessly recurring spell-copying engine by perpetually targeting itself with Return to Action. Whenever the Mage enters the battlefield, its triggered ability intercepts the original sorcery to create a self-targeting copy that ensures it always comes right back when sacrificed. Woe Strider provides the necessary sacrifice outlet to trigger this return, turning every iteration into a clean, repeatable cycle. As a bonus, sacrificing the Mage to Woe Strider lets you scry 1 repeatedly while filtering through your graveyard and generating an endless stream of triggers.