After looking into this staff further, it hardly feels like a good reward for saving Kagha and the Grove. Think about it. It doesn't provide a +1 or anything to hit or damage. It allows you to basically cast Entangle, a Level 1 Druid spell, once per day. The only good thing it does is allows you to walk on vines created by the Entangle spell so that you can get close and smack those you entangle.
Nature's Snare seems better than this staff, and you just find Nature's Snare in a chest. If you hit with it, you have a chance of ensnaring enemies. That seems a bit better than once per day you can cast Entangle.
Instead, I was thinking this seems more appropriate, or something similar:
“The Staff is called Paleoak,” she then told Wynari. “It is infused with Silvanus' strength. These staves are gifted to Faithwardens who act in defense of nature. They provide the wielder with Faithwarden's Vines. Faithwarden’s Vines is a Conjuration Spell similar to Entangle. Vines sprout from the ground in a 20 foot square, turning it into difficult terrain and entangling creatures within. Entangled creatures cannot move.” An ally, however, could use its help action to try to tear away the vines. The range of the spell was 60 feet, and the spell required Concentration. However, it was always prepared, and the user received a +4 to their Spell Save DC so when enemies tried to resist via a Strength save, the DC would be 4 higher than the spellcaster’s actual Spell Save DC. “The duration is for 1 minute. It recharges once per long rest, so a Faithwarden can only use it once a day.”
“Besides this,” Kagha continued, “it also imbues the wielder with Faithwarden's Stride. Druidic vines cannot Ensnare and do not create difficult terrain for you. Please. Use this staff well.”
This, at least, makes it so that it is harder for enemies to escape the Entangle spell. Instead of like a DC 12 Strength save, or whatever, it would now be something like 14. So with this special staff that you can only cast once per day, you might be able to entangle a bunch of enemies for 10 rounds far more easily than the standard Entangle spell could. Thus, it makes the staff more special, more powerful, and a true reward for your hard work. However, it still isn't too OP, because you can only use Faithwarden's Vines once per day.
