Ulvenwald Tracker
Creature — Human Shaman
, 
: Target creature you control fights another target creature.
"Okay, listen, it's 'GRAAAAAR!' not 'rawr.' 'Rawr' isn't going to scare anyone. Now, let's try again...."
Aya Kakeda
Secret Lair Drop (SLD)
• #1283Rulings
The second target of Ulvenwald Tracker’s ability can be another creature you control, but it can’t be the same creature as the first target.
(wotc • 2017-03-14)
If either target of Ulvenwald Tracker’s ability is an illegal target when the ability tries to resolve, neither creature will deal or be dealt damage.
(wotc • 2017-03-14)
Rulings
The second target of Ulvenwald Tracker’s ability can be another creature you control, but it can’t be the same creature as the first target.
(wotc • 2017-03-14)
If either target of Ulvenwald Tracker’s ability is an illegal target when the ability tries to resolve, neither creature will deal or be dealt damage.
(wotc • 2017-03-14)