How would a house-rule allowing a person attacking a Device to target only part of it work?

Question

Within M&M 3E, there's the Removable Flaw for powers that turns them into items that are worn or carried that can be damaged or removed. The following rule states how the Toughness is calculated:

Devices have a base Toughness equal to the total points in the device divided by 5 (rounded down, minimum of 1).

One of the noted issues is that nothing makes these items inherently PL-limited for damage resistance, which means a Battlesuit character like the archetype might be rocking a Toughness bonus of +26, which, when paired with the +8 defense, means the battlesuit is PL 17 defensively. Other than requiring players to break up their Devices into smaller ones that keep closer to PL, I was considering making it easier to target individual parts of the suit, say trying to take the flight systems (16 pp, thus +3 Toughness) down.

I've been considering allowing an attacker to choose to only target part of the system rather than the entire whole, trading off a (potentially much) lower Toughness bonus for the defender against not being able to disable the entire Device with a lucky hit. I'm debating between making this common to everyone (maybe including a penalty to the attack similar to what's present for Disarm, Trip, and Smash attacks), requiring an Advantage (which might just remove the penalty from the prior option), or rolling this into the Precise Extra, which is already supposed to let the person use the power more precisely. Drawbacks I can think of:

• Toughness potentially being much lower than expected. Aspects with 24 or less PP only have a +4 Toughness possible. Against a Damage 10 attack, standard for the PL 10 game, that means you will take damage on anything less than a Natural 20, and on a roll of ten or below, the Device suffers three degrees of failure, and is destroyed.
• The effects on the wearer of the Device could be much more severe. The example Battlesuit has armor plating that provides Protection 11 (Impervious). Destroying that armor plating would happen about half the time on a successful hit, as per the last point's calculation, and would remove 11 points of Protection, leaving the Battlesuit wearer at a +1 Toughness bonus, a bit worse than the average gang member.
• Canny players may try to target said systems under the quanta for a higher Toughness since it's every 5 points.
• Original Device Toughness and this idea of Toughness of parts don't necessarily scale with PL

Unfortunately, I don't have a gaming group to test this with right now.

Answer 1

This was brought up in a recent episode of Mutants & Masterminds Monday, where Alex Thomas and Steve Kenson responded on the topic.

Alex Thomas

What I would do in that situation is I would ... have them, if they don't have a Nullify power for it, I would have them power stunt a Nullify for the effect that they're trying to switch off ... and have that be an opposed check by the ranks of the power that they are trying to switch off of the device total so if they're trying to switch off the device's force field it would be their Nullify rank versus the force field's Toughness rank and just handle it that way. That seems like the easiest way to me.

Steve Kenson

Yeah, I agree with Alex. I think that a lot of it depends, like a lot of things in Mutants & Masterminds the answer depends on what it is you're trying to do exactly. If ... you're trying to attack a smaller part of a device in order to disable it then I agree with Alex's solution, basically what you're trying to do is Nullify a device's power essentially so you should probably go with something like that...

He then went on to discuss the use of alternative defenses and Power Attack because the scenario raised in the chat was of a "giant robot" rather than the intended powersuit/comprehensive Device.