no fiendish chain most certainly does not negate attacks, if the card does not state it negates an attack it does not negate attacks
Yes. Effect Veiler can chain to their activations in the main phase, and Fiendish Chain can chain to them at any time outside the damage step (meaning if they are attacked and flipped, it can't negate them).
If a monster activates an effect, then Fiendish Chain can be chained to this. Fiendish Chain will resolve first, meaning the monster's effect will be negated when it tries to resolve. So if Chaos Sorcerer activates his Ignition Effect, Fiendish Chain can be used to negate it.
The turn player has Priority, so can activate Chaos Sorcerer's effect as chain link 1. Fiendish Chain can be chained to this. Fiendish Chain will resolve first, so Chaos Sorcerer's effect will be negated when it tries to resolve.
Yes. Once Red-Eyes Darkness Metal Dragon is successfully summoned, there is a summon response window for cards like Bottomless Trap Hole. Only Spell Speed 2 or 3 effects can be used here. You can therefore use Fiendish Chain against it, which will resolve if not negated. That means that when Red-Eyes Darkness Metal Dragon is able to activate its Ignition Effect, it will be negated when it tries to resolve. However it is worth noting that you could always wait until Red-Eyes Darkness Metal Dragon tries to activate the effect, and chain Fiendish Chain to it, it will resolve first and therefore negate the dragon's effect too. So hitting it before it can activate is not actually necessary.
The damage negating portion of the effect is a lingering effect applied by the resolution of its Ignition Effect. If you chain Fiendish Chain to Tomahawk's activation, all parts of the effect will be negated. However if you allow it to resolve, and only use those cards on it later, it will not do anything to the lingering protective effect. So yes, you can negate the effect on your own Number 42: Starship Galaxy Tomahawk, but you will not get any Battle Eagle Tokens either meaning there's little point to it. Note that Effect Veiler can only target a monster the opponent controls.
When the Monarch is tribute summoned, it has a triggered effect that activates. Fiendish Chain can be chained to this. Fiendish Chain will resolve first, meaning the Monarch effect will be negated when it tries to resolve.
Yes. Effect Veiler can chain to their activations in the main phase, and Fiendish Chain can chain to them at any time outside the damage step (meaning if they are attacked and flipped, it can't negate them).
If a monster activates an effect, then Fiendish Chain can be chained to this. Fiendish Chain will resolve first, meaning the monster's effect will be negated when it tries to resolve. So if Chaos Sorcerer activates his Ignition Effect, Fiendish Chain can be used to negate it.
The turn player has Priority, so can activate Chaos Sorcerer's effect as chain link 1. Fiendish Chain can be chained to this. Fiendish Chain will resolve first, so Chaos Sorcerer's effect will be negated when it tries to resolve.
Flip Effects are Triggered Effects, so if a player flipped a flip effect monster, the effect will trigger as chain link 1. Fiendish Chain can be chained to it, to negate the effect when it tries to resolve. However, if the monster is flipped by an attack, then the trigger happens during the Damage Step. There are restrictions against what you are allowed to activate during the damage step, and Fiendish Chain can't be used here. So it could not stop a Flip Effect at that time.
No. Because Fiendish Chain targets a monster, Obelisk the Tormentor will not be affected by it.
Yes. Fiendish Chain would work on Azure-Eyes Silver Dragon on it's summoning effect. The moment Azure-Eyes is summoned you can chain link Fiendish Chain to Azure-Eyes's effect creating a chain link 2. It would resolve as chain link 2: Fiendish Chain, then chain link 1 Azure-Eyes effect.
Yes. Kasha's effect to return all monsters to deck is a triggered effect, triggered on special summon. Fiendish Chain can be chained to this, and will resolve first. That means Kasha's trigger will be negated when it tries to resolve, and nothing will be shuffled back into deck. Kasha's ATK will remain at 0.
Yes. Once Red-Eyes Darkness Metal Dragon is successfully summoned, there is a summon response window for cards like Bottomless Trap Hole. Only Spell Speed 2 or 3 effects can be used here. You can therefore use Fiendish Chain against it, which will resolve if not negated. That means that when Red-Eyes Darkness Metal Dragon is able to activate its Ignition Effect, it will be negated when it tries to resolve. However it is worth noting that you could always wait until Red-Eyes Darkness Metal Dragon tries to activate the effect, and chain Fiendish Chain to it, it will resolve first and therefore negate the dragon's effect too. So hitting it before it can activate is not actually necessary.
Machine Gearframe has a triggered effect and an Ignition Effect, and one final effect that counts as the effect of a spell card. If Fiendish Chain is used on it while it is a monster, then the first two effects will be negated when they try to resolve. Machina Gearframe will not be able to turn itself into an Equip Card. However if Machine Gearframe has already become an equip card, then it's now considered a spell card, so Fiendish Chain can't be used on it here. It can therefore summon itself back into the monster zone, this can't be stopped.
It doesn't matter who started with Priority, the simple matter is, if a monster has an activated effect, then Fiendish Chain can be chained to it. Fiendish Chain will resolve first, and the monster effect will be negated before it can resolve. The main problem is against monsters that tribute themselves as a cost such as Exiled Force or Stardust Dragon. Because they leave the field as the cost of their own activations, Fiendish Chain would not be able to target them.
Fiendish chain stays targeted to the monster and negates its effect when you enter end phase