I’ve started playing again after many years. I like card games and transitioned to this after having my first kid and selling my physical cards. After a few weeks back I’ve found Imbue to be very imbalanced. Its a very cool concept and it could work but the infinite value scaling is just far too strong.
Most cards that give universal cost reduction, free casts, or free units are balanced around vulnerabilities like removal. However Imbue is literally impossible to interact with besides one card that makes it cost more for one turn which is very very weak as the hero powers are 2 mana MAX. The lack of interaction, aside from being unfun, is extremely strong.
Now to point out the imbalanced value aspect of Imbue. Typically a minion cards value is based around its attack and health. Almost every imbue creature has fantastic stats, PLUS imbue the hero, PLUS amd third effect. Take the pally dragon. 3 mana 3/4, already a good value. Imbue, amazing value. Deathrattle imbue again, far too much value for 3 mana! Same with the 5 cost 4/5 taunt imbue divine shield. SO MUCH VALUE!
Lastly, the imbue mechanics scale almost infinitely. If a pally has a perfect run for 6 turns and gets imbue to trigger as well as activate his power each time you will have, for the cost of 6 mana, 12 dragons costing 6 mana each that play on draw AND draw again! Thats 72 mana of value from 6 mana!?! Priest? 2 mana for a choice of spells or creatures to cast each turn scaling with imbue. Mage? Unblockable unpreventable and untauntable damage PLUS minions flooding the board every turn. All of them scaling with infinite value. By getting imbue to 4 your hero power is now beginning to be more powerful than many legendaries for just 2 mana.
At least one of these categories needs to be tweaked. Minions should have weaker stats to justify the other abilities. Or make the power more interactive to opponents. Give the hero power health that an opponent can hit to keep it from being activates next turn. (Just an example of interaction, not intended to be balanced) Put a limit on the scaling or effects. Make paladin portals lock in the level of the dragon when cast and dont scale it up with each imbuenfor example. Not all chamges are needed, but something has to give because the imbue is just frequently unpleasant as it is.
Just the views of an old MTG player after several weeks.