stack metamagic?

[isildur]

"An empowered, maximized spell gains the separate benefits of each feat: the maximum result plus one-half the normally rolled result. An empowered, maximized fireball cast by a 15th-level wizard deals points of damage equal to 60 plus one half of 10d6."(phb1)

this rule is applied to any mm feat?

for example, an 20lv wizard cast empower, maximize, energy admixture, twin fireball(he has arcane thesis, metamagic school focus feat)

then final damage is 60(maxi)+5d6(empower)+10d6(energy admixture)+10d6?

or this rule is only applied to empower and maximize.

then final damage is {(60+5d6)+(60+5d6)}*2

which one is right?

i think second one is right. because, what about empower, enlarge fireball.
10d6 damage flys 2560ft, and 5d6 damage just flys 1280ft? it's rediculus.

[Esgath]

When do “add-on” effects such as poison occur? For example, if an assassin delivers a death attack with a weapon bearing wyvernpoison, does the poison take effect first, thus potentially reducing the target’s Fortitude save against the death attack?
As a general guideline, whenever the rules don’t stipulate an order of operations for special effects (such as spells or special abilities), you should apply them in the order that’s most beneficial to the “controller” of the effect. In this case, the assassin is the “controller” of both the poison and the death attack, so he’d most likely choose for the poison to take effect first,and then the death attack.
The underlined part is the only time I know of, this was addressed officially. So you can pick what's best for you.

[KillianHawkeye]

That particular interaction is not a general rule. It is specific to Empower + Maximize.

[Emperor Tippy]

"An empowered, maximized spell gains the separate benefits of each feat: the maximum result plus one-half the normally rolled result. An empowered, maximized fireball cast by a 15th-level wizard deals points of damage equal to 60 plus one half of 10d6."(phb1)

this rule is applied to any mm feat?

for example, an 20lv wizard cast empower, maximize, energy admixture, twin fireball(he has arcane thesis, metamagic school focus feat)

then final damage is 60(maxi)+5d6(empower)+10d6(energy admixture)+10d6?

or this rule is only applied to empower and maximize.

then final damage is {(60+5d6)+(60+5d6)}*2

which one is right?

i think second one is right. because, what about empower, enlarge fireball.
10d6 damage flys 2560ft, and 5d6 damage just flys 1280ft? it's rediculus.

{60 (Maximized Fireball) + 60 (Maximized Energy Admixture) + [10d6/2] (Empowered Fireball) + [10d6/2] (Empowered Energy Admixture)}*2 (Twin)

Or 240+ [((10d6/2)+(10d6/2))*2].

Add on an Archmage's Mastery of the Elements to flip the whole thing to whatever energy type bypasses your targets defenses and you are golden.