Yeah, Upgrade | Downgrade is good card design.
Toadfish | Pufferfish is not (according to the general community).
Unfortunately, your card falls into the latter category. No offense, but the fact that the upgraded can interact with the unupgraded does not sufficiently warrant making them the same card. Should Congeal have Shockwave's effect instead of its current effect? Should upgraded Maxwell's Demon have Fire Nymph's ability instead of "paradox"?
You call using an upgrade bonus "lazy", well, throwing that word around is a double-edged sword, because I call not spending the time to develop a proper card name and theme for a mechanic "lazy."
Completely changing the card when upgrading it should not be a gimmick to avoid using an upgrade bonus. Thematically*, it should be something with a deep connection to the idea of the card. Very few card ideas can pull this off successfully, as you can tell because I the only one I can cite is Upgrade | Downgrade. And none of the cards in the game have reached this standard - the only one that has tried is Firefly | Elite Firefly, and I don't think it pulls it off very well.
At the very least, change the upgraded card's name from "proxy" to something that's tastefully in the same ballpark as the unupgraded card,
but actually refers to the effect on the card.
*Mechanically, you could justify it for a card where you don't want 6 of Mechanic A and 6 of Mechanic B in a deck, so you balance it by having them suffer a shared 6-copy limit. But yeah, no one successfully designs cards off mechanics anymore...
I think you should explain how this card works better, the current explanation in the notes section is either incomplete or misleading. From what's there, this is what I gathered:
You have Sky Blitz in your hand. You draw a Proxy. Until either player plays a card, the card functions as a Relic, i.e. you can click on it repeatedly but it just drains 4
each time without being cast as a spell. You play Sky Blitz. Proxy immediately changes into a Sky Blitz for 4
. Now, you can play it since you did not need to cast Proxy for it to copy the effect. Double Sky Blitz for 9
, 4
, no hassle.
If you need to play it for it to copy the card, then that's still not too bad. You could probably splash 1 or 2 into any Chaos Wyrms deck without much hassle.