These changes seem good! Though empowered speed would be nice to keep on U2 seeing as its nice to have a mobility champ in a theme with low range
You are a bit late to the party last expansion zeya used that for infinite rumblers / screechers and he did very well with it, but I do agree with the above and its not unreasonable to tweak it
you dont see a problem with removing champions with short lived while gaining 50% nora cost. I wish you were trolling.
This is a clear example of unintended synergies causing over-efficiencies. It's happened before, many times, where an interaction/ability has been in the game for years without notice/problem and all of the sudden is a huge issue (Aquatics, for example). Deal with the unintended synergies. Move the abilities way from those synergies and replace them with other cool abilities.
What would be the downside if we removed the negative cost (The ability would cost 0 instead of -10) and slightly increased the % return to offset. Ability would be the same but would reduce its effectiveness as a first turn drop and on low cost (Rumblers) targets.