Does elemental affinity and radiant soul stack?

Yes, these 2 effects will stack.

Does magic missile work with empowered Evocation?

Magic missile 3 bolts. Empowered Evocation does benefit magic missile’s damage roll.

Does elemental affinity work with scorching ray?

You can do it every time you roll damage associated with your draconic ancestry. There is no other limitation. But you can add it to one damage roll meaning if you cast scorching ray you can add this damage to only one ray.

Does elemental affinity work with Cantrips 5e?

Since cantrips are spells, and Elemental Affinity lets you add your Cha mod to damage when you cast a spell, Elemental Affinity applies to cantrips (that deal the appropriate type of elemental damage, of course).

How many times can I use empowered Evocation?

Empowered Evocation applies to one damage roll each time you cast an evocation spell. There is no mention of only allowing this ability to be used once per any form of rest.

Does empowered Evocation work on scorching ray?

Empowered evocation works with 1 damage roll per spell. Scorching ray rolls separate damage for each ray. Fireball or magic missile only roll once. I would think that with magic missile, the bonus would only apply to one missile if you target multiple creatures with it.

Does elemental affinity work with twinned spell?

Twinned Spell turns the affected spell into such a case, meaning that you roll the damage once. As such, both targets are affected by Elemental Affinity. when you cast a spell that deals damage of the type associated with your draconic ancestry, you can add your Charisma modifier to one damage roll of that spell.

Does elemental affinity work with blood?

Elemental Affinity is a talent in Divinity Orignal Sin 2. The corresponding surface for each magic is as follows: Fire surface for Pyrokinetic, Water and ice surfaces for Hydrosophist, Poison/oil surface for Geomancer, Electrified surface for Aerothurge, and Blood surface for Necromancer.

Is magic missile one damage roll?

For magic missile, you do not roll 3d4+3 and apply the total to everyone. The Magic Missile is not treated as one boom but as actual separate missiles that you can divide up as you see fit. Your right they are separate missiles. So you roll 1d4+1 for each individual missile.

How many times can you use empowered Evocation?

Can you twin spell Eldritch Blast?

As soon as you hit level five, Eldritch Blast becomes capable of targeting more than one creature, which makes it ineligible for twinned spell.

Can you twin haste 5e?

Haste lets you make attack rolls that can affect more than one creature before the spell expires. So haste is not a valid spell for twinning.