And now, for my analysis!
First off, this card is just straight up good. As noted in above posts it’s effectively a 3 mana 5/4 on your opponents turn. Add in the fact that it also has frenzy, if your opponent can’t clear it they will have to position awkwardly. It’s incredibly costly to clear this with board + general because it’ll trade with pretty much every minion if the general attacks first or it’ll deal tons of damage if a minion attacks first.
Honestly, this is probably going to just be to the go-to neutral 3 drop for filler. I don’t think it’ll be in every deck as some factions have three drops just as good as this, e.g. Silverguard Knight, Songhai’s clogged 3 slot, Ragebinder, so on and so forth.
But wait! You then start considering the faction synergies. This card is going to be CRAZY for Kaleos. Consider: Kaleos clears your board with a MDS’d Katara and plays a Wild Tahr on the same turn. Unless you’re Vanar you probably will not have an answer in hand for both of these. This puts you in a serious catch 22 situation.
Kaleos is also undoubtedly the general who can utilize the Frenzy most effectively. Even without the attack buff it remains impactful because of Inner Focus, Blink, MDS, Jux, etc. So the contingency of it’s effect (that is, the opponent has to attack) is not nearly as relevant as it is for other factions. Dealing with this thing is probably going to be a nightmare and then some.