This should give you 1d4+3 force damage per dart created by magic missile.

For your example, if a magic item grants 1 to spell DC, +2 spell attack rolls and +2 to spell damage, then due to its wording it would increase spell damage by 2 whenever damage from a spell is calculated. (I would rule that a non-damaging spell would not be affected since it wouldn't have a damage formula to increase or a damage type.) In this example, magic missile would deal extra damage on each dart.

Jeremy Crawford indicates in a question about Empowered Evocation which is similar that you should determine the damage for a single dart and use that for every strike. (Your DM may decide to roll each dart's damage separately, but you should still get to add all of your bonuses to each dart.)

https://twitter.com/jeremyecrawford/status/557820938402947072

Q: say you have +3 to spell damage from feature. Magic missile 3 bolts. +3 per bolt or flat +3?"

 

A: Empowered Evocation does benefit magic missile's damage roll.

 

Q: x per bolt,even on same target?

 

A: Yep. It's one damage roll, just like fireball, but that roll can damage the same target more than once.

In general, it depends.

Since this question started out very generically.

The exact wording of the feature that grants the extra damage is very important. If the spell has to be a hit (which requires an attack roll), sometimes a save, and sometimes it just has to deal damage, or be qualified in some other way.

The 1st level Warlock spell Hex adds an extra 1d6 necrotic damage whenever you hit with an attack. So this would not apply to saves or spells like magic missile that don't require an attack roll or a save.

Knowledge Clerics gain Potent Spellcasting at level 8, where they add their wisdom modifier to the damage of any cantrip. This would apply to any damaging spell.

Evocation Wizards gain Empowered Evocation at level 10. This feature adds their intelligence modifier to the damage of any wizard evocation spell. This would apply to any wizard evocation spell, whether it used attack rolls or saves. Magic Missile is such a spell.

This should give you 1d4+3 force damage per dart created by magic missile.

For your example, if a magic item grants 1 to spell DC, +2 spell attack rolls and +2 to spell damage, then due to its wording it would increase spell damage by 2 whenever damage from a spell is calculated. (I would rule that a non-damaging spell would not be affected since it wouldn't have a damage formula to increase or a damage type.) In this example, magic missile would deal extra damage on each dart.

Jeremy Crawford indicates in a question about Empowered Evocation which is similar that you should determine the damage for a single dart and use that for every strike. (Your DM may decide to roll each dart's damage separately, but you should still get to add all of your bonuses to each dart.)

https://twitter.com/jeremyecrawford/status/557820938402947072

Q: say you have +3 to spell damage from feature. Magic missile 3 bolts. +3 per bolt or flat +3?"

A: Empowered Evocation does benefit magic missile's damage roll.

Q: x per bolt,even on same target?

A: Yep. It's one damage roll, just like fireball, but that roll can damage the same target more than once.

In general, it depends.

Since this question started out very generically.

The exact wording of the feature that grants the extra damage is very important. If the spell has to be a hit (which requires an attack roll), sometimes a save, and sometimes it just has to deal damage, or be qualified in some other way.

The 1st level Warlock spell Hex adds an extra 1d6 necrotic damage whenever you hit with an attack. So this would not apply to saves or spells like magic missile that don't require an attack roll or a save.

Knowledge Clerics gain Potent Spellcasting at level 8, where they add their wisdom modifier to the damage of any cantrip. This would apply to any damaging spell.

Evocation Wizards gain Empowered Evocation at level 10. This feature adds their intelligence modifier to the damage of any wizard evocation spell. This would apply to any wizard evocation spell, whether it used attack rolls or saves. Magic Missile is such a spell.

This should give you 1d4+3 damage per dart created by magic missile.

For your example, if a magic item grants 1 to spell DC, +2 spell attack rolls and +2 to spell damage, then due to its wording it would increase spell damage by 2 whenever damage from a spell is calculated. (I would rule that a non-damaging spell would not be increased since it wouldn't have damage to increase or a damage type.) In this example, magic missile would deal extra damage on each dart.

Jeremy Crawford indicates that you should determine the damage for a single dart and use that for every strike. (Your DM may decide to roll each dart's damage separately, but you should still get to add all of your bonuses to each dart.)

https://twitter.com/jeremyecrawford/status/557820938402947072?lang=en

Empowered Evocation does benefit magic missile's damage roll. Yep. It's one damage roll, just like fireball, but that roll can damage the same target more than once.

In general, it depends.

Since this question started out very generically.

The exact wording of the feature that grants the extra damage is very important. If the spell has to be a hit (which requires an attack roll), sometimes a save, and sometimes it just has to deal damage, or be qualified in some other way.

The 1st level Warlock spell Hex adds an extra 1d6 necrotic damage whenever you hit with an attack. So this would not apply to saves or spells like magic missile that don't require an attack roll or a save.

Knowledge Clerics gain Potent Spellcasting at level 8, where they add their wisdom modifier to the damage of any cantrip. This would apply to any damaging spell.

Evocation Wizards gain Empowered Evocation at level 10. This feature adds their intelligence modifier to the damage of any wizard evocation spell. This would apply to any wizard evocation spell, whether it used attack rolls or saves. Magic Missile is such a spell.

This should give you 1d4+3 force damage per dart created by magic missile.

For your example, if a magic item grants 1 to spell DC, +2 spell attack rolls and +2 to spell damage, then due to its wording it would increase spell damage by 2 whenever damage from a spell is calculated. (I would rule that a non-damaging spell would not be affected since it wouldn't have a damage formula to increase or a damage type.) In this example, magic missile would deal extra damage on each dart.

Jeremy Crawford indicates in a question about Empowered Evocation which is similar that you should determine the damage for a single dart and use that for every strike. (Your DM may decide to roll each dart's damage separately, but you should still get to add all of your bonuses to each dart.)

https://twitter.com/jeremyecrawford/status/557820938402947072

Q: say you have +3 to spell damage from feature. Magic missile 3 bolts. +3 per bolt or flat +3?"

A: Empowered Evocation does benefit magic missile's damage roll.

Q: x per bolt,even on same target?

A: Yep. It's one damage roll, just like fireball, but that roll can damage the same target more than once.

In general, it depends.

Since this question started out very generically.

The exact wording of the feature that grants the extra damage is very important. If the spell has to be a hit (which requires an attack roll), sometimes a save, and sometimes it just has to deal damage, or be qualified in some other way.

The 1st level Warlock spell Hex adds an extra 1d6 necrotic damage whenever you hit with an attack. So this would not apply to saves or spells like magic missile that don't require an attack roll or a save.

Knowledge Clerics gain Potent Spellcasting at level 8, where they add their wisdom modifier to the damage of any cantrip. This would apply to any damaging spell.

Evocation Wizards gain Empowered Evocation at level 10. This feature adds their intelligence modifier to the damage of any wizard evocation spell. This would apply to any wizard evocation spell, whether it used attack rolls or saves. Magic Missile is such a spell.

This should give you 1d4+3 damage per dart created by magic missile.

For your example, if a magic item grants 1 to spell DC, +2 spell attack rolls and +2 to spell damage, then due to its wording it would increase spell damage by 2 whenever damage from a spell is calculated. (I would rule that a non-damaging spell would not be increased since it wouldn't have damage to increase or a damage type.) In this example, magic missile would deal extra damage.

In general, it depends.

Since this question started out very generically.

The exact wording of the feature that grants the extra damage is very important. If the spell has to be a hit (which requires an attack roll), sometimes a save, and sometimes it just has to deal damage, or be qualified in some other way.

The 1st level Warlock spell Hex adds an extra 1d6 necrotic damage whenever you hit with an attack. So this would not apply to saves or spells like magic missile that don't require an attack roll or a save.

Knowledge Clerics gain Potent Spellcasting at level 8, where they add their wisdom modifier to the damage of any cantrip. This would apply to any damaging spell.

Evocation Wizards gain Empowered Evocation at level 10. This feature adds their intelligence modifier to the damage of any wizard evocation spell. This would apply to any wizard evocation spell, whether it used attack rolls or saves.

This should give you 1d4+3 damage per dart created by magic missile.

For your example, if a magic item grants 1 to spell DC, +2 spell attack rolls and +2 to spell damage, then due to its wording it would increase spell damage by 2 whenever damage from a spell is calculated. (I would rule that a non-damaging spell would not be increased since it wouldn't have damage to increase or a damage type.) In this example, magic missile would deal extra damage on each dart.

Jeremy Crawford indicates that you should determine the damage for a single dart and use that for every strike. (Your DM may decide to roll each dart's damage separately, but you should still get to add all of your bonuses to each dart.)

https://twitter.com/jeremyecrawford/status/557820938402947072?lang=en

Empowered Evocation does benefit magic missile's damage roll. Yep. It's one damage roll, just like fireball, but that roll can damage the same target more than once.

In general, it depends.

Since this question started out very generically.

The exact wording of the feature that grants the extra damage is very important. If the spell has to be a hit (which requires an attack roll), sometimes a save, and sometimes it just has to deal damage, or be qualified in some other way.

The 1st level Warlock spell Hex adds an extra 1d6 necrotic damage whenever you hit with an attack. So this would not apply to saves or spells like magic missile that don't require an attack roll or a save.

Knowledge Clerics gain Potent Spellcasting at level 8, where they add their wisdom modifier to the damage of any cantrip. This would apply to any damaging spell.

Evocation Wizards gain Empowered Evocation at level 10. This feature adds their intelligence modifier to the damage of any wizard evocation spell. This would apply to any wizard evocation spell, whether it used attack rolls or saves. Magic Missile is such a spell.