A while back, I remember Vroomfogle(?) suggesting an incremental Haste. I like the idea and thought about working it into the game..
You start with a %Act increase at low level (+20%Act/lvl, maybe) and eventually work it up to 200%, 300% or more for the highest level spells. This is how most other things in RM are handled; small increases over time.
VladD, the only "problem" I've encountered with ADD is downtime. Fight or Flight situations make focusing easy. Cops and snipers and air-traffic controllers all benefit and many are predisposed. People have carried spears and defended perimeters far longer than setting those spears aside to farm. Not all of us got the memo.
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totally agree that the %Act is bonus enough! I don't give a + to init for Haste. If PC's want a bonus to MM, then use the added %Act to prep/set up the maneuver.
The heart attack option is a good control; similar to my Haste addiction. But it might already be present in the MM table. Just sub a "broken arm/spine" for heart attack. Your games definitely have consequences! I'd love to play.
The fantastic number of attacks mentioned, can also be a liability. Often, the enemy will be defeated before the final attack roll. But you've already declared the attacks so changing actions is a penalty, changing targets is a penalty and if you have to run up to another opponent, there's an OB and init penalty. IF the opponent survives the barrage, their DB is applied to each attack, RAW.
Another liability is Translocation spells. Or anything that requires a Situational Awareness: Combat roll/Surprise roll. "The total of the maneuver roll indicates what %Act is available for the reaction" SoHK, . Now maybe you can double this if PC's are Hasted/Adrenal Speed. Or just say that they have their full %Act, but reacting to
this event is restricted by the roll. For now, I go with the former. The Mage realizes that after the Monk spends the time to set up Adrenal Speed and Haste, it might not be a good time to use translocation spells on him.