So my question is if you can cast 3 full spells in one round using Action Surge and the War Caster Feat. 

Example: I have a enemy 30ft away from me and I cast Blight at him (hit or miss), then I use Action Surge to cast another Blight spell at the same target (hit or miss), I then use my movement to move up to them. My turn is over and now it's the enemies turn and because he is hurting bad he moves away from me, but I then have a opportunity attack so I use my reaction and use the War Caster Feat and cast another Blight spell at him. 

Is any of these possible or am I wrong?

Thanks for the help Brian_Avery. I was also using the Blight spells as a example and I could've used all 1st Level Spells or 2nd Level Spells, it was just a example. 

Also on the part where I said my turn was over and that I could cast 3 spells in one round was that the initiative order hadn't come around to me again, which technically means it's still in one round of combat. 

Plus, wouldn't the example you gave about the enemy holding their action to run away when triggered by you coming within melee range, wouldn't that be meta-gaming?

Once again thanks for the help. 

Bonus Action: any level spell with 1 bonus action casting time or any level spell with 1 action casting time cast using Sorcerer Quicken Spell metamagic or similar feature.

Main Action: cast a cantrip with casting time of 1 action.

Action Surge: cast any level spell with casting time of 1 action.

Move to enemy.

Reaction: when enemy moves out of melee threat range of you on their turn and you have Warcaster feat you can cast any level spell that targets only that enemy.

Result: 4 spells in one round.

Your action surge would still have to be a cantrip of one action if you're going by the rules in the PHB. It states that if you use a spell as a bonus action then for the rest of the turn you can only cast a cantrip with a casting time of one action. Action surge, by the definition under Fighter, is still within the same turn.

With War Caster it looks like you could cast Blight again on your reaction. Not seeing anything that disagrees with that.

So, Blight, cantrip, cantrip. Reaction; Blight.

Quote from Unicornucopiaclear >>

Your action surge would still have to be a cantrip of one action if you're going by the rules in the PHB. It states that if you use a spell as a bonus action then for the rest of the turn you can only cast a cantrip with a casting time of one action. Action surge, by the definition under Fighter, is still within the same turn.

 

 Incorrect. If you cast a spell as a bonus action you cannot use Action Surge to cast an Action spell (it would have to be a cantrip). But if both spells require an action, you can cast one with your action, then the other with your Action Surge. 

It's important to differentiate, as the rule for casting you're referring to is specifically under the heading for casting as a bonus action.

Jeremy Crawford confirmed this interpretation in a Sage Advice.

Which is to say that the OP is correct, though Cyb3rm1nd is incorrect.

Quote from MellieDM >>

Quote from Unicornucopiaclear >>

Your action surge would still have to be a cantrip of one action if you're going by the rules in the PHB. It states that if you use a spell as a bonus action then for the rest of the turn you can only cast a cantrip with a casting time of one action. Action surge, by the definition under Fighter, is still within the same turn.

 

 Incorrect. If you cast a spell as a bonus action you cannot use Action Surge to cast an Action spell (it would have to be a cantrip). But if both spells require an action, you can cast one with your action, then the other with your Action Surge. 

It's important to differentiate, as the rule for casting you're referring to is specifically under the heading for casting as a bonus action.

Jeremy Crawford confirmed this interpretation in a Sage Advice.

Which is to say that the OP is correct, though Cyb3rm1nd is incorrect.

 Fair enough!

Consider also casting Blight, moving to the enemy, casting Dissonant Whispers, forcing him to move away, and casting Blight as your Reaction on your turn as you force your opponent to use his Reaction to flee.

How does vicious mockery force an enemy to move away? Also, most forced movement don't provoke opportunity attacks if I recall correctly

Woops I did mean Dissonant Whispers.

Editing the above.

What's special about Dissonant Whispers that allows for the Oppertunity is that it forces the opponent to use their Reaction to move. You only get Oppertunity if the opponent uses their Movement, Action (including Bonus), or Reaction.

Quote from BDaddLy >>

Woops I did mean Dissonant Whispers.

Editing the above.

What's special about Dissonant Whispers that allows for the Oppertunity is that it forces the opponent to use their Reaction to move. You only get Oppertunity if the opponent uses their Movement, Action (including Bonus), or Reaction.

 Wow,  you're right. Interesting :) From the rules:

You also don't provoke an opportunity attack when you teleport or when someone or something moves you without using your movement, action, or reaction. For example, you don't provoke an opportunity attack if an explosion hurls you out of a foe's reach or if gravity causes you to fall past an enemy.