Hearthpwn

I think people vastly overstate the power of this card. It's pretty much a dead draw later in your deck, because nobody wants to play a vanilla 8 Mana 8/8 in 2024. You first need to draw this and then be lucky enough to be able to (and want to) play adjacent cards to hopefully crank this out at a somewhat early turn. And even then a vanilla 8/8 on turn 4 or 5 generally won't be a problem for most decks to deal with.

I predict this card won't see play, unless some aggro deck gets some really nifty tools to reliably make use of it.

That seems way too cheap for all slow decks. Probably an auto include on every single one of them. I won't be surprised if most mid range decks run it (or OK some of them).

much better than azerite giant

I think an Elemental deck could summon this on...turn 4 or five depending on your luck, and any deck that can dump its hand pretty fast like Pirate Demon Hunter. But then if is worth playing a vanilla 8/8 is another debate. As for Giants, I think is a very solid one. Probably the Best Neutral Giant since Naga Giant .

This art is ridiculous. Immediate favorite of mine.

For most decks, the earliest this is realistically hitting the board is Turn 4. That's not bad by Giant standards, around the time when Mountain Giant of yore was ready.

The problem is reliability though. If your Red Giant is sandwiched between 2 expensive or situational cards, good luck playing it for a good while. This can be mitigated by building a low curve aggro deck, one which aims to leverage Red Giants as a midgame stat bomb to overwhelm opponents. Sure, it may not be as dependable as old Mountain Giant, but you can play it on 4 without giving up the board. 

I initially dismissed this as a junk rare, but now I kinda see the vision. It doesn't seem too terrible if you work around it. 

Pairs nicely with a cheap drink