Okay, some adjusting is needed.
Mercenary 4
3|5 -> 2
3|5
Charger 5
4/5 (momentum) -> 5
7/5 (momentum)
Current Minotaur 4
3.5 (avg)|5 -> 4
5.25 (avg)|5
Currently, unupped minotaurs are better than a merc on average (assuming all attacks connect). Upped, 2 mercs are better than 1 minotaur. Both are probably weaker than a charger. Also, as mentioned, adding momentum to the upgraded version weakens it overall. However, in the nature of aesthetics, let's make this card reflect its namesake's power.
Proposed change:
Power un-upgraded increased to 4 (average of 5.25)
Power upgraded (or unupgraded + momentum) increased to 5 (average of 6.5)
Power upgraded plus momentum is 6 (average of 7.5)
Cost raised by one to 5.
This creates some interesting choices. Un-upgraded, it's slightly stronger than a charger, but has no momentum. With momentum played on it, it's only 0.5 stronger than a charger with an extra momentum put on it. 1.5 stronger than one with out. Upgraded, it's slightly weaker than a charger, but when a momentum is played on it, it's 0.5 stronger again.
Thoughts?