Opinions are conflicted on Warcraft as a good or bad film, but most seem to agree that the computer-generated imagery is superb. If you're curious for more details on how the effects were accomplished, this 20-minute BBC doco should do the trick.
Warcraft's visual effects were cooked up by Industrial Light & Magic, who set out to kick the VFX for the orcs out of the park. And having seen the film myself I can say, yep, the orcs look good.
But ILM managed to give the spell-slinging in the movie its own look too. Ben Schnetzer, who plays Khadgar, explains how some of these shots were set up:
We would have light and electrodes rigged up to us to give a lighting effect in real time, so that in post they're working off of actual light reflecting off surfaces. And then they fill in all the craziness.
He also provides some insight as to how much the actors had to work with, in terms of sets and practical effects versus CGI:
I'd say about 40 per cent of what we were working with was practical and it was real and tactile ... and then the other 60 per cent ... you're taking a leap of faith.
Warcraft 2016 The Future of CGI [YouTube]