But it should be possible to get High Fenrir to lvl 50 if you're playing long enough to have participated in the first races. As far as I remember @Nynaevelan's explanation it is possible to (legitimately) have up to 4 High Fenrirs + one may have obtained a few orbs in the heroic race (I got 25 High Fenrir orbs from one of the races). So, recalling 3 Fenrirs, fed to lvl 40, would give you 3x100=300 orbs, so if you have 25 more from one of the heroic chests - you can empower it twice. Of course, you may have even more of the orbs if you paid your way to lap 50 in the recent races.
Now imagine what a 10 level difference, with an extra advantage of two "empowerment" stars would do in a combat.