In shore, you can ignore this rule safely.
I don't mean, "you can play the game without it," although you can, and many people do.
I mean, "If you're a mage, and your GM enforces the rules about casting in heavy armor, as described by the book, wear heavy armor anyway."
Because the rules as written don't really do anything other than annoy the GM who has to roll all the dice.
Pasted from a previous most of mine discussing this rule:
...any TW device ignores the penalties for armor, so it's only proper spellcasting that's an issue.
More importantly, the penalties doen't really matter.
+20% cost on PPE means that a spell that costs 10 PPE now costs 12 PPE.
Big whoop.
A Ley Line Walker in RUE starts off with 3d6x10+20+PE PPE, so an average first level LLW has 135 PPE.
Wearing the proper armor, he can cast Fire Bolt (for example) 19 times.
Wearing the wrong armor, he can only cast Fire Bolt 16 times.
Believe it or not, that extra three castings isn't going to matter 99.99% of the time.
Most mages don't actually deplete their PPE reserves on anything resembling a regular basis.
What's more, on low level spells, the penalties literally do not matter at all.
Globe of Daylight has a PPE cost of 2.
120% of 2 is 2.4, which rounds right back down to 2 again.
Which means that there is ZERO difference cost-wise between casting that spell wearing LLW armor and wearing Heavy Deadboy.
Now you're thinking that high level spells are probably where it makes a difference.
Say you're spending 600 PPE on Teleport: Superior, wearing the wrong armor would bump that up to 720, a full 120 PPE!
Big whoop.
In order to cast that kind of spell, a mage has to have extra PPE coming from somewhere anyway: ley line nexus, blood sacrifice, borrowing from other people, or a crapload of talismans, etc.
And I can't think of ANY of these methods where getting an extra 120 PPE would be significantly harder than getting the initial 600 to begin with.
As for the other penalties, take a look at that table again and do the math.
There's a 20% chance that no penalties kick in.
There's a 20% chance each that damage/effects OR duration OR range OR range + duration are affected.
So you cast Fire Bolt, and what's the potential problem?
Well, range could be affected... but I've rarely seen anybody cast spells at maximum range, so that's not going to be a problem except in very rare cases.
Damage could be affected, and that'd possibly suck... but there's only a 20% chance of that happening.
And in those 20% of case where you cast Fire Bolt and your damage IS reduced, it's reduced by 1d4x10%.
If you roll average damage for your Fire Bolt, that's normally 14 MD.
IF the damage ends up being reduced, that means there's a
25% chance that you instead inflict 13 MD (big whoop)
25% chance that you instead inflict 11 MD
25% chance that you instead inflict 10 MD
25% chance that you instead inflict 8 MD
Which means that the 20% of the time that damage being nerfed matters, it's not going to make a heck of a lot of difference about 75% of the time, IF that: remember, the GI-Joe rule means that small damage differences like this probably don't matter anyway.
Or let's say that you cast Magic Net instead.
The range is normally 60', the damage is zero, and the duration is 30 seconds per level of the caster.
Right off, there's a 40% chance that the spell isn't affected at all, because you either roll the that no problems occur or that a problem with damage occurs.
20% of the time, range will be decreased. With a range of 60', this means that there's a 25% chance each time range IS affected of the new range being:
54'
48'
42'
36'
Most likely the first 6-12' isn't going to determine whether or not the spell hits the target, so there's only about a 50% chance that the range difference is going to matter, less if you take possible range issues into account when casting spells in the first place.
20% of the time, the duration is going to be reduced by 1d4x10%.
So instead of 30 seconds per caster level, the spell will instead last:
27 seconds
24 seconds
21 seconds
18 seconds
Per level.
At first level, that might make a difference, but probably not much of one since the people are still going to be immobilized for over a full melee round minimum.
And there's a 20% chance that both range and duration are reduced by 20%, so the spell will have a range of 48' and a duration of 24 seconds per level.
Which, again, isn't really going to matter the vast majority of the time.
Or say you cast a spell on yourself, something like Fly As The Eagle.
Damage isn't an issue, and range isn't an issue. The only element that could be affected that matters is duration.
So if you roll that duration alone is affected, that means that instead of 20 minutes per level, you get:
18 minutes per level
16 minutes per level
14 minutes per level
12 minutes per level
None of which is really likely to matter. If you cast the spell in combat, even at 12 minutes you're not going to have to worry about the duration running out on you before combat is long over.
For non-combat usage, like long-range travel, you're going to have to cast the spell multiple times anyway, at low level at least.
So I'd say there's something like a 10% chance of it mattering, in the 20% of the time that duration happens to be affected anway.
None of the above is really an incentive to not wear normal body armor.
What IS an incentive for mages to not wear body armor is that now everything you do takes longer.
You can't just cast Fire Ball, then roll for damage.
You have to cast Fire Ball, then roll to see what (if anything) aspect of the spell is reduced, then you have to roll again to see by how much, and if those results might matter, you have to do the math to find out exactly what's going on.
And you have to discuss from time to time with the GM whether PPE cost is rounded up or down, and whether Mega-Damage should be rounded up or down, and other piddly little disagreements might arise because Palladium was (according to you) so offended at people ignoring the original rules that they came up with a bunch of useless and more complicated rules for those same people to ignore (not to mention a large number of other people who followed the original rules, but avoid the new mess that was created).
Now, different people have different styles, and different luck, so some people's experiences may differ from what I'm projecting there.
If so, feel free to explain how the mage armor rule itself significantly impacted your gaming experience.
Not just fear of the rule- not just avoiding casting spells, or avoiding heavy armor, because you were afraid of what might happen, but actually rolling on the charts and having a spell go wrong as described by the rules when casting in heavy armor.