Mitheirn uses the rules for Mutants & Masterminds, Second Edition. Many of these rules have been modified to fit the themes and tone of heroic fantasy. This section will cover rules changes that have not been previously addressed. Most of these modifications are inspired by suggestions in the Mastermind's Manual for M&M2E.
As explained on pages 11 and 152 of M&M2E, when you roll a natural 20 in combat, you always hit. If you roll a natural 1, you always miss your attack. These modifications only apply to combat.
In Mitheirn, on a natural roll of 20, the result adds +10 (for a total of 30). A natural roll of 1 reduces the result by -10. So if you have an attack bonus of +12 and roll a natural 20, your final total is 42. If you roll a 1, your attack total is 2. This rule is explained on page 8 of the Mastermind's Manual.
These critical dice results may also apply to saving throws, but not ability checks or damage rolls.
When a character wishes to push the limits of his magic, then he may use extra effort. This gives him the same basic benefits as listed in M&M2E, pages 120-121, with a few modifications. Extraordinary effort, as outlined in the Mastermind's Manual pages 82-83, is also permissible.
The benefits of extra effort may include adding +2 to a single ability, skill or magic check, not including attack rolls. Extra effort may increase a magical effect by 2 ranks for one round, or permit the character to use a magic item at its full Power Level. There are many more options suggested in M&M2E or MaMa.
The power stunt may allow the caster to add the Action Power Extra to a spell, casting it with less than a Move action. The surge may allow a second spell to be cast in a round.
Any use extra effort on a spell or inherent power increases the Magic cost by +2, and will autocmatically cause either a fatigue condition or 1 point of Backlash. A hero point may counter either the fatigue or backlash cost. Twice a day, 2 Mana may be spent from a mystic focus to absorb a fatigue condition without spending a Hero point.
Extraordinary effort allows you to gain up to 5 levels of extra effort, paying for this either with hero points or a maximum of 3 fatigue conditions. Extraordinary effort with magic always adds +1 Backlash point per level of extra effort that cannot be paid for with hero points. Up to 4 Mana may be spent from mystic focus to absorb fatigue conditions from extraordinary effort..
A Last-ditch Effort is an extraordinary effort that is paid for with damage results, in a progression of staggered, disabled, unconscious, dying.
When using Extra Effort with an Ability check, you may suffer ability strain rather than fatigue. You may take -1 to the ability for each extra effort use, which recovers at a rate of 1 every 6 hours.
Drawbacks are described on pages 124-127 of the Mutants & Masterminds, Second Edition. These are expanded to allow mental and social drawbacks as well. These drawbacks follow the same basic rules as outlined in M&M2E. The drawback's value depends on the Frequency that it comes up in play and the Intensity of the drawback. Because mental drawbacks and social drawbacks may appear quite often, the value of frequency may need to be reduced by the GM.
No character may have more than 10 additional points from drawbacks. You may take all the drawbacks you wish; these additional drawbacks may hamper you, but you don't get any more points from them. Drawbacks that are added by a racial template are not counted against this limit.
Uncommon drawbacks only take place once in a while or in unusual situations, and are worth +1 power point. Common ones come up once a week or more often, or may appear in circumstances you can expect to end up in often, and are worth +2 power points. Very common ones are circumstances that show up almost every day, or are part of your normal routine, and are worth +3 power points.
Minor drawbacks have a DC of 5 to overcome or barely affect you, and aren't worth additional power points. Moderate drawbacks have a DC of 10 to overcome, may have a noticeable impact on you, and are worth +1 power point. Major drawbacks have a DC of 15 or more to overcome, may greatly impact your capabilities, and are worth +2 power points.
Heroic fantasy inevitably leads to situations where the only good solution is drawing a sword or axe and chopping the problem down to size. The combat rules can be found on pages 150-171 of Mutants & Masterminds, Second Edition. There are a few changes for Mitheirn.
These are replaced by a natural 20 adding +30, and a natural 1 subtracting -10 from the relevant values. This results only apply for attacks and saving throws, not for ability, skill, power checks or damage rolls.
A critical hit occurs when you roll within the weapon's threat range to hit, and the result is high enough to hit your target's defense. This adds +5 to the damage result. You may choose to forgo the damage bonus to add another effect to your attack equal to 2 ranks in either Fatigue, Dazzle, Drain (Strength), Nauseate, or Stun.
A critical miss may take place when you roll a natural 1 in combat, and the total hit result is negative. For example, if your Attack bonus is +3 and you roll a 1, your final attack total is -7. This causes a critical miss. However, if your attack bonus is +12 and you roll a 1, your result is +2, and so you do not risk a critical miss. You may make a Dexterity check, DC 10, to merely miss and be flat-footed until your next action. If you fail the check, then the critical miss could make you lose your next standard action while fumbling your weapon, may make you accidentally strike a nearby ally or yourself, or may cause you to have a -4 penalty to your next attack roll.
Delaying an action in a round does not change your initiative order in following rounds. There is no limit to how long you can delay your action within a single round, although if you do not act by the end of the round, the GM will begin counting the initiative order again from first to last, and you will act as normal in the next sequence.
Mutants & Masterminds combat is meant to be freeform in terms of character movement, but ranges and movement speeds may be more important in a fantasy adventure game. While tactical movement is not recommended for all combat scenes, large-scale or certain fight scenes, such at rambling over ancient ruins or wading through dank caverns, might be enhanced by knowing how far you can move in a single round.
Characters normally have three kinds of movement: Normal, 30 feet; Accelerated, 60 feet; and All-out, 120 feet. A character can make a normal move in a move action, accerlated move in two move actions or one standard action, and an all-out move in a full round.
Those characters with movement powers calculate their tactical movement differently. As explained in the Power Alterations section of the Magic page, tactical movement for spells or inherent powers are calculated using the base movement of the power.
A power's normal tactical movement is equal to 30 feet + 5 feet per rank. Accelerated movement is 60 feet + 10 feet per rank. All-out movement is 120 feet + 40 feet per rank.
When you are attacked, if you have not taken an action, you may either default to Total Defense (+4 dodge bonus) or a defensive action from a feat.