This makes it a 2/3 with nothing else around, which makes for a great two turn play, and then in the later game you can put the counter somewhere more meaningful
Zendikar had a strong counter and token theme (as many of my designs do), and it was the perfect fit
If another creature would enter the battlefield with a number of +1/+1 counters on it while you control Benevolent Hydra, it enters with that many counters plus one
Again, the color identity rule is in play here
In fact, Aftermath shows off a number of characters whove lost their sparks, including Ob Nixilis, Nissa, Nahiri, Sarkhan, Kiora, Samut, Calix, and, most disappointingly for the fans hes picked up in recent stories, Tyvar
That's Waylay in a nutshell: nerfed but still gigging Viashino Sandstalker since 1997, but not the best when you're stuck at one mana