MoO Today, MoO Everyday (A Beginner's Guide to Interrupting)

Interrupting is a key part to success in Wildstar.  It determines a number of factors from how fast you burn a boss / mob to how much damage your party will ultimately take.  There are many mobs abilities and bosses that can be interrupted, and a good rule of thumb is whenever you see red telegraphs, get to interrupting!

That being said, a good interrupt addon is a must in Wildstar, I would recommend either Zinterrupt or Interruptor, both linked here.  For interruptor when a mob starts casting an ability you will see the following obvious bar appear on the screen:

1. Test cast will be the name of the ability
2. The bars beneath the casting bar is the number of Interrupt Armor (IA) the caster has, which in this case are green and blue.
3. The green bars are armor that has already been taken off, the blue bars are armor that remains.

So let's take a look at Interrupt Armor (IA)

Interrupt Armor - Enemy NPCs like players have interrupt armor on them.   You have probably seen this icon next to a creatures portrait or health bar somewhere in the game.   This icon has a number on it, that number also represents the number of interrupt armor something has.  For players as well as NPCs IA prevents the application of CC effects.  This means that if a target has IA on the following cannot happen to them:

• Blinds;
• Disorient;
  
• Knockdowns; and
• Stuns

Basically whenever any of the above are applied to a PC or NPC with IA, the blind, disorient, or knockdown, eats a stack of IA.  So for example;

Tier 4 Zap removes 2 IA.  The target has 2 IA, so the number 2 is on the icon next to the portrait of the target or interrupt shows 2 blue bars.  The target gets Zap with tier 4 Zap, but wait a minute it didn't get stunned?  What happened?

The target has 2 IA armor so it at the whole effect of Zap, so even though it has no IA now, it is still free to do what it wants.  But wait,  same scenario, but Obstruct Vision (OV) is also on your LAS for example, see Engineer Tank guide.  You throw OV and then throw tier 4 Zap at the same target.  Suddenly its stunned.  That's because OV removes 1 IA, and tier 4 Zap removes 2.  So when OV was applied,  it left the target with 1 IA, which Zap destroyed leaving the second part of Zap, the part that can still stun free to pass through and stun the target.  Note, that if you have used Zap first then OV, nothing would have happened.  Why?

OV only removes armor, it does not stun, Zap however does.  So be careful reading tool tips.  Certain abilities stun, while others just remove IA.

Here's a visual example for an esper:

If you interrupt a NPC properly, getting pass all  its IA, while it is casting an ability, you will see its health turn purple.  This is MoO (Moment of Opportunity)  when this happens the target takes double damage in addition to not being able to get its ability off.  Win, win.