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
Look at how different he is compared to the two more standard 'elemental of the forest' creatures we have above
A lot of what you want to hit right now with this is Fear of Missing out and Agathas Soul Cauldron, so you will get the effect and get it early when you want the Lander token
Caesar leans into making a lot of little creatures fast taking advantage of Anim Pakal, Myrel, and tried and true Darien and really showcases on blacks desire for sacrifice and reds need for Burn
Also, this was printed after planeswalkers, so it protects them too, and is the only one of these four to do so
Given the nature of Commander, its highly likely each opponent will have a robust board when you reach this chapter