Found 2 interesting behaviors while creating an attack boost with negative ep regen:
1 - Ep will fall into negative values and continue to drop. I think that values should not drop past zero.
2 - Units will get stuck when ep is in negative values. Probably due to every skill having a minimum ep cost of zero. And since ep is now less than zero basic skills (move, hold, produce, harvest) are no longer able to be performed.
There are potential uses for these behaviors, so I would not like to change the behaviors themselves.
Instead I propose to add a definable minimum value of ep, so attackboosts cannot lower ep below a certain point. If the values drop toward extreme negatives (-50 for example) then units will be paralyzed for incredible periods of time, so long that forgetting about that unit and just building another feels like the more time effective solution. What I think needs to happen is to have an optional minimum parameter added to the Max-Ep line, which sets the minimum limit the amount ep can drop to (via negative EP regeneration) in the unit xml:
<max-ep value="6" regeneration="1" minimum="-10" />
If the minimum tag is not found then a minimum of 0 should be the default.