It's a super expensive combat trick that's always going to cast at least RR. If you're casting this for 2-3 mana in a red deck, you've probably already won.
I disagree with this. In a vacuum, or in previous years I might agree, but looking at reds three drop section in particular in the past few years, we’ve got loads of token generators. Hanweir garrison alone makes this a 3 drop. Tokens have increased over the last few years and this might be a legitimate contender for cube. There are plenty of games I swing with a hanweir garrison and don’t autowin.
But then the big problem is that it's not so impressive on such a board. Cool, your Garrison is now a 3/4 with double strike and trample. Assuming it connects, you turned RR into 4 extra damage and a leftover thing to equip on future turns... that's not all that great?
The optimal case here feels like paying something like 2RR and tacking this on to Thrun or another card which protects itself. I think this card is one of those that gets substantially better the lower your environment's power is. It'll be a menace in ELD limited but it's not something I'm looking to try out in my cube.