Been playing 47 days straight and have yet to get a legendary from the horn. I thought there was a pity system set up for all this stuff? There seems to be for dice but not the horn. IMO horn should produce a legendary once every 20 days max.
#horn summon is booty
hard surge
north flicker
Don't worry, you'll get one in the end. I'm at day 73 and have yet to receive an epic.
See it as freebies and not as an actual source of good champs.