Empower Spell

Type of Feat: Metamagic
Prerequisite: Ability to cast 2nd-level spells.
Specifics: All variable, numeric effects of an empowered spell are increased by 50%. For example, an empowered magic missile deals one and one-half times normal damage (1d4 + 1 multiplied by 1.5).
( 1d4 + 1 ) * 1.5 Empowerment does not increase spell duration.
The actual implementation varies.
Some spells like Ray of Enfeeblement have a dice roll(1d6) and a level bonus (+5). In some cases the level bonus is empowered too(Ray of Enfeeblement, Combust) and in some cases only the dice roll is empowered(Finger of Death, Slay Living).
Most of the time empower spell is implemented as: nDamage + nDamage / 2, using integer division that rounds down. This rounding effect is more pronounced with spells that use a single dice, such as Mirror Image, Cloudkill, Touch of Idiocy
Use: An empowered spell occupies a spell slot two levels higher than normal. Saving throws and opposed rolls, such as those made when Dispel Magic is cast, are not affected.
For a list of all spells which can be enhanced by this feat, see: :Category:Spells that can be Empowered.
== Notes ==
Empower spell is a feat available to spellcasters. It increases a spell's numerical effects by 50% in exchange for placing the spell two levels higher. A common tactic with wizards is to empower fireballs and lightning bolts.
A comparison of Empower Vs Maximize that goes over the benefits of each, and to help you decide what to take.
Clerics of the Healing domain cast certain healing spells as if they have Empower Spell upon them, but they do not possess this feat. They may purchase this feat as normal.
== 3.5E comparison ==
The empower effects are dictated to only work on variable rolls, not any additional modifiers, unlike the feat's description.
For instance, Magic Missile, the damage should be:
 ( 1d4 * 1.5 ) + 1
Not:
 ( 1d4 + 1 ) * 1.5
The spells themselves give both types in a variety of ways, so no standard seems to be applied to this feats use in spell scripts, most likely bugs, because all new spells (and some changed old ones) use the new NWN2 function ApplyMetamagicVariableMods() (in nwn2_inc_metmag.nss) which does the calculation correctly It only does the calculation correctly, if the main script passes the correct parameters, which is not the case with Magic Missile, even though the updated version does use the ApplyMetamagicVariableMods, but it passes the wrong parameters, empowering 1d4+1 instead of 1d4 only:
int nDam = d4(1) + 1;
nDam = ApplyMetamagicVariableMods(nDam, 5);
ApplyMetamagicVariableMods is not designed for special cases like this. It's only designed for spells like Cloudkill that don't have fixed additional damage. It would require a new function to distinguish between random roll and fixed extra damage. Either that, or use the old way of calculating metamagic damage:
int nRoll=d4();
int nDam = nRoll + 1;
if (GetMetaMagicFeat() == METAMAGIC_MAXIMIZE)
{
nDam = 5; //5 points damage max if maximised
}
if (GetMetaMagicFeat() == METAMAGIC_EMPOWER) 
{
nDam = 1+ nRoll + (nRoll/2); //empowered magic missile damage range from 2 (1+1+0.5=2 rounded down) to 7
}