If you can trigger the second ability, which requires two hits in most cases, the doubling of counters is massive, especially in Nayas colors
It has payoffs for two of the three types of modified, and then limits the counters to only going onto creatures who already have them
It is a little mana intensive, so playing it in a two or three-color deck might be difficult
Permanent spells that were countered earlier in the turn never entered the battlefield, so they won't be legal targets for Brought Back
Opponents cannot allow Etali to sit on the battlefield unopposed and attack, or they'll quickly find themselves losing
The need to have other creatures keeps it fair, but a 2-mana vigilance creature is still a decent body, especially with that ceiling so high I can barely see it