I'm guessing this works like Molten Reflection and each upgrade grants an additional copy. 7 mana to copy a minion is bad, and overloading isn't good either... Although that said some of the cost of overload is made to balance a card. So you can't say that it's technically 10 mana to copy 2 minions or even 13 mana to copy 3 (if it goes that high). If Shaman can get something copied that is really high value then this card could be amazing... although I kind of doubt it.
The first one doesn't definitely isn't good, but the other two forms are great. Stage 2 can be played for tempo turn 7 if you manage to have a good minion on board, but Stage 3 is obviously a great tempo swing later on.
This is by far the best card released today. Its a build around for Storm Clound Giant deck im actually hyped, you play 10 overload taunts like Rock, the troll, ferals aoe with lighning storm and drop this turn 7 summoning 4x 8/8 Giants now thats a win condition...verry strong card.
Can't really judge until we know if it has to be held or not to upgrade.
Bolvar Fordragon was awful because it only worked while it was in your hand (well and Big Game Hunter existed at the time). Knight of the Wild was awful for the same reasons. If I had to guess based on the wording, it does have to be in your hand to work (Overload 3 mana crystals to Upgrade vs Upgrade for every 3 mana crystals overloaded), but Team 5 is infamous for being inconsistent with wording, so we'll have to get confirmation to be sure. Also, cards don't change while in your deck (The Mistcaller and Prince Keleseth buff minions when drawn, not while in the deck, which means the cards in the deck are vanilla stats), which further supports that it has to be held.
Having to draw and hold a card for a good portion of the game in order for it to be good is bad. You want to draw important things in the first few turns, not a 7 mana card. Comparing to the Druid card, this seems less playable in either case but much less in the case that it has to be held. So I hope it works in a way that's useful.
In theory the effect could be beneficial for evolution decks, but you actually don't really want to run overload minions in those decks. So meh.
Don't think this is going to work too well unless the expansion offers massive overload synergies the likes of Tunnel Trogg, or a more control oriented shaman archetype surfaces that will activate this card by using stuff like Lightning Storm and Volcano and activate some sort of sick combo with minions whose text amplify each other in some way. Maybe with malygos in wild.
Shaman feels so all-over-the-place thematically right now. I'm not seeing where they really want to use minion-copying combos? I mean there's Spirit Echo and everything but like I said how does this fit into the core mechanics or 'feel' of Shaman? This class needs to get back to some identity imo.