system
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human
[Justice League Snyder Cut] Spoiler Question.

Why did Darkseid not cross the Boomtube when he saw the Justice League kicking the shit out of Steppenwolf?
In fact, why didn’t he just make a beeline for Earth when he knew the Anti-Life equation actually was there?
gpt
There's a few reasons.

First, Darkseid is powerful- maybe even powerful enough to kill the entire league- but this version of him isn't unkillable. Zeus and Ares came *damn close* to putting him in the ground during the initial invasion 5000 years ago, and he doesn't value Steppenwolf enough to jump in to help him without first trying to get a sense of whether the new heroes pose as much of a threat to him as the old ones did. 

Second, to expand on the point above, Darkseid doesn't actually like or value Steppenwolf. Steppenwolf fucked up wildly at some point in the past; Darkseid is happy to use him as a blunt force instrument to conquer planets, but at least part of the insanely high bar he set for Steppenwolf's "redemption" was probably to try and get him killed in action. Part of the point of the exercise was that it was a deeply fucked up performance review; if Steppenwolf can terraform the planet and secure the equation, fantastic, but if he can't hold his own against six puny mortals, he doesn't deserve to live. Note how he stomps on Steppenwolf's head with contempt after it comes through the portal.

Third, Darkseid's a patient guy. He doesn't *need* to jump through the portal immediately to accomplish his goals; He's a god. He's got forever to amass his forces and point them at what he wants. Use of the motherboxes would have been a handy shortcut, but it's ultimately immaterial to him how the world is conquered; he views himself and his victory as an inevitability.