Nice strength, strong traces, neat effect. So what's the problem ? Cost, of course.

If you seek for a taxing sentry with a strong stopping power, Data Raven fits better - unless the runner goes tag-me, but Kitty makes this strategy less viable than it was.

If you want to stop the Runner to run over and over, Excalibur is nice - while it's unique and doesn't allow what Uroboros could make (stopping the run and being on several server), it's way cheaper.

All of that makes Uroboros a sad snake. Someone to hug him ?