Gnome BODY (important!)

It's significantly more complicated than that.  That's for a very particular energy input distributed over an entire hemisphere, from outside the atmosphere.  Bundle that energy into a kilometer-thick death ray and you'll see vastly different results.  Bundle that energy into a different form, like kinetic energy or a different frequency on the EM spectrum or "cosmic energy" and you'll again see vastly different results.  Apply that energy to the planet at ground level and you'll see, you guessed it, vastly different results. 

Making your words sound like ExampleMan's is INT.  It's 100% about experiencing, recalling, and reproducing a sensory stimulus. 
Acting like ExampleMan, including picking the same words ExampleMan would, is Acting and thus PRE. 
Successfully imitating ExampleMan for an extended period is INT and PRE. 

Thank you so much, Gnome BODY and Ninja-Bear

I don't see how one can earn a -1/4 limitation on a power by defining that it takes a full phase to activate (which is mechanically what OIAID does) and then eliminate the limitation by spending 5 points on instant change, but then still retain the -1/4. 

Maneuvers do not modify END cost.  A Strike, a Haymaker, and a Martial Strike all cost the same amount of END.  (Unless performed with different powers or amounts of STR, of course). 
 
Talents vary, and you should check the Talent writeup directly.  For example, Deadly Blow costs END in 5th but not in 6th because the way it was built changed. 

Maneuvers do not modify END cost.  A Strike, a Haymaker, and a Martial Strike all cost the same amount of END.  (Unless performed with different powers or amounts of STR, of course). 
 
Talents vary, and you should check the Talent writeup directly.  For example, Deadly Blow costs END in 5th but not in 6th because the way it was built changed. 

The OIAID transformation is a Full Phase.  You can't Abort if you've already taken your Phase.  "Attack" has nothing to do with it, blowing your actions on anything locks out Abort until next Segment.  I've already cited page numbers for this, see the last thread we were talking about Abort in. 

This is just how I adjudicate complex gestures vs regular gestures.  Other GMs may adjudicate otherwise.
 
If you have no issues doing something else with your hands, it's not worth the limitation gestures.  
If you can do something else with your hands but it might ruin what you are doing unless you succeed on a Dex roll, its normal gestures.
If you can't do something else with your hands, its complex gestures.

Why are most of you listing special effects rather than mechanics?  This is Hero - the fact that you are playing Stairway to Heaven with a full band rather than Chopsticks on a cheap keyboard is just special effects.  What does it do in gameplay?
 
Thanks to IndianaJoe3 for providing the mechanics.

"Complex Gestures" are in Fantasy Hero pg 285. It's a skill roll penalty, or forces a DEX roll if the spell does not require a skill roll.

The difference between Gestures and Complex Gestures is just that a part of the Special Effects of the power becomes more complex, and therefore potentially more likely to fail or be stopped, and less likely to be replicable. For you to cast a spell that takes Complex Gestures, for instance, might mean that you have to be able to move your fingers in certain positions which you couldn't achieve if, for example, you were in a car accident that damaged the nerves in your hands. On the other hand, simple Gestures might allow you to do the same spell without even having that hand, because you just need to point your wrist in the right direction, since you have the special effects saying that your will to make magic happen is focussed enough that missing a hand is not an impediment. In this instance, "Gestures" is something like pointing roughly in the direction you want the spell to go, while "Complex Gestures" is a precise way of holding your fingers, while pointing exactly at the target.
 
Basically, if you want more of a limitation from the Gestures limitation, you take it as a Complex Limitation to let the GM know that this is your power's weakpoint, more so than ever.

This is absurd.  Gandalf970 asked a very straight-forward question with a very straight-forward answer and nobody's managed to even touch on it. 
 
@Gandalf970 Reference FREDp296, FREDp297, 6E1p381
 
All that's needed to disrupt casting is to land an attack that's not totally negated by defenses.  A single point of STUN or other such effect is enough to cancel the entire spell. 
The procedure thus becomes holding one's action until the caster casts, winning the DEX vs DEX roll to act first when the caster casts, hitting, and dealing any damage.  This negates the spell, with nothing the caster can do at this point. 
 
6E's Fantasy Hero contains text on page 165 that indicates Gestures and Incantations begin at the start of the Segment, and thus holding until the caster's DEX and the DEX vs DEX roll are unnecessary, making the process even easier.  Just go first on that Segment and hit them. 

The pedantic programmer in me says "Well that's just configuration data, the program was probably totally gone.  He probably just missed a tickbox.".  He is then immediately shouted down by the security security guy in me going "WHY THE EXPLETIVE WOULD THEY LEAVE LOGIN DATA AFTER AN UNINSTALL!  EXPLETIVE THAT'S BAD!" and the tinkerer in me going "Well I just tried it and there wasn't any tickbox he could have missed.". 
I only put up with the blasted thing because my entire social circle recoiled at the mention of IRC like vampires exposed to a cross. 

VPPs must have a tightly defined SFX.  No vaguely defined "cosmic power VPP (does anything)" or "magic VPP (does anything)". 
You, the player, cannot have the Extra Time Limitation.  When your Phase comes up, you either have the thing you want to VPP fully built or you're not VPPing that thing right now. 
 
These were in response to the guy who took a Cosmic  "magic" VPP as his character's only mode of combat and would take three minutes just to figure out that Fireball is RKA 2d6 AoE.  It was horrible. 

And when the GM asks for help or guidelines, this doesn’t help.

Think of 11+OCV as (11+OCV)-, then think of DCV as a penalty.  Thus 6 OCV guy has a 17- "Hit things".  A 5 DCV foe applies a -5 penalty to that.  End result is that this character has a 12- to hit this foe. 
In fact, you can just bake the 11 in.  6 OCV guy should just write 17- as his OCV.  Then, to borrow your wording for skills:
"The more OCV you have, the higher the OCV number. Someone with 17- in OCV is more skilled than someone with 15-. When you perform an attack, you need to perform within your capabilities. In other words, you need to roll your OCV number or less. If you roll really low, it means you nailed it! If you roll high but still make it, it means you just squeaked by.  But the other guy is trying to not get hit, so they apply their DCV as a penalty to your OCV number."
 
Alternatively, flip to a roll-over system like you described.  There's no rules police who will kick down your door for having fun the wrong way. 

Think of 11+OCV as (11+OCV)-, then think of DCV as a penalty.  Thus 6 OCV guy has a 17- "Hit things".  A 5 DCV foe applies a -5 penalty to that.  End result is that this character has a 12- to hit this foe. 
In fact, you can just bake the 11 in.  6 OCV guy should just write 17- as his OCV.  Then, to borrow your wording for skills:
"The more OCV you have, the higher the OCV number. Someone with 17- in OCV is more skilled than someone with 15-. When you perform an attack, you need to perform within your capabilities. In other words, you need to roll your OCV number or less. If you roll really low, it means you nailed it! If you roll high but still make it, it means you just squeaked by.  But the other guy is trying to not get hit, so they apply their DCV as a penalty to your OCV number."
 
Alternatively, flip to a roll-over system like you described.  There's no rules police who will kick down your door for having fun the wrong way. 

Think of 11+OCV as (11+OCV)-, then think of DCV as a penalty.  Thus 6 OCV guy has a 17- "Hit things".  A 5 DCV foe applies a -5 penalty to that.  End result is that this character has a 12- to hit this foe. 
In fact, you can just bake the 11 in.  6 OCV guy should just write 17- as his OCV.  Then, to borrow your wording for skills:
"The more OCV you have, the higher the OCV number. Someone with 17- in OCV is more skilled than someone with 15-. When you perform an attack, you need to perform within your capabilities. In other words, you need to roll your OCV number or less. If you roll really low, it means you nailed it! If you roll high but still make it, it means you just squeaked by.  But the other guy is trying to not get hit, so they apply their DCV as a penalty to your OCV number."
 
Alternatively, flip to a roll-over system like you described.  There's no rules police who will kick down your door for having fun the wrong way. 

VPPs must have a tightly defined SFX.  No vaguely defined "cosmic power VPP (does anything)" or "magic VPP (does anything)". 
You, the player, cannot have the Extra Time Limitation.  When your Phase comes up, you either have the thing you want to VPP fully built or you're not VPPing that thing right now. 
 
These were in response to the guy who took a Cosmic  "magic" VPP as his character's only mode of combat and would take three minutes just to figure out that Fireball is RKA 2d6 AoE.  It was horrible. 

let's not deviate from the topic of conversation

Fantasy Hero 5th edition, example magic systems section.  11 out of 12 systems presented have Gestures and/or Incantations.  The last does not have the SFX of gestures or incantations so cannot be the magic system used by the OP who mentions gestures and incantations.  The baseline is clearly for Gestures and/or Incantations. All evidence supports OP using a magic system where spells have Gestures or Incantations. 
There's one bit of my evidence, still haven't seen any of yours. 
 
You don't get to say you're bowing out unless you actually stop arguing.  Claiming to leave an argument is not a get-last-word-in-uncontested free card. 
 
Do you have a single iota of evidence that Gestures and Incantations aren't in use?  Remember, we're not discussing the vague abstract of all possible magic systems, we're discussing OP's magic system.  And OP mentioned "gestures or incantations".
 
In this thread, this is the only important part of your post. 

And I don't feel that deliberately refusing to engage with the topic the OP wants to discuss when they have a question on the grounds that there might be houserules or nonstandard methodologies when the OP suggests standard methodologies and mentions no houserules is constructive.  In fact, I think it's extremely rude to the OP and has no place in a thread where they're looking for rules answers. 
 
Do you have a single iota of evidence that such is the case in OP's game, given their explicit mention of "gestures or incantations" as a trigger for an attack? 
 
You might want to reread some Fantasy Hero books, because Gestures and/or Incantations is in fact the base condition. 

No problem. 
I don't think rewording the question would help, alas.  A number of users on this forum don't care if you want RAW.  They want to theorycraft and be inventive and that's great, but not when somebody's asking about the rules as they're written or a particular construct. 
  
Emphasis mine.