1.2.6 Volstagg Eiso8 (Gain one stack of Well Fed each round)
1.2.6 Fandral Eiso8 (Master of bad puns, Witty Retort causes Migraine)
1.2.6 Hogun Eiso8 (Immune to Winded, Off-Balanced, Fumbling and Flanked)
2.1.1 Rogue Eiso8 (Starts Combat with Into the Fray)
2.1.2 Sabretooth Eiso8 (Gain Frenzy at the start of combat, but can't survive being KO'ed)
2.1.5 Hercules Eiso8 (Chance to counter area attacks with Column Down)
2.1.6 Deadpool Eiso8 (The first attack that would reduce DP's health to 0 will return him to 50%)
2.1.6 Cable Eiso8 (Chance to pre-counter attacks)
2.2.1 Hercules Aiso8 (S3 Gift of Battle grants Rising Up & Breakthrough)
2.2.3 Captain America Eiso8 (Chance to counter ranged attacks with Shield Throw)
2.2.3 Vision Aiso8 (S4 now exploits Radiation and gains Phased Advantage)
2.2.4 Deadpool Eiso8 (Still Better, Come At Me, Bob)
2.2.4 Wolverine Eiso8 (Hunting Instinct)
2.2.4 Hank Pym Aiso8 (S2 gains Hobbled : Attacks cannot be Stealthy)
2.2.4 Wasp Aiso8 (S1 causes Incapacitation)
2.2.5 Luke Cage Aiso8 (S3 applies Reduces damage from counter attacks and follow-up attacks)
2.2.6 Scarlet Witch Eiso8 (Chaos Shield never misses and never fails)
2.2.6 epic Scarlet Witch Aiso8 (S4 has a chance to cause Biofeedback, DarkVoid, Deathfrost, Radiation Exposure, or Soulfire)
2.2.6 epic Scarlet Witch Aiso8 (S4 has a chance to apply CosmicEnergy, ForceField, Recuperation, Regeneration, or TeresingBoost)
2.2.6 Quicksilver Eiso8 (Quickness is not consumed by counter attacks)
2.3.1 Doctor Doom (Immune to Stun and Exhaustion)
2.3.2 Magik Aiso8 (S1 get additional soulcharge)
2.3.2 Moonstone(Chance to counter attacks fr enemies with Cower,Distracted,Disoriented,Intimidated,Shell Shocked)
2.3.2 Ms. Marvel (Ms. Marvel's attacks gain Truestrike and Guaranteed Hit)
2.3.4 Hank Pym Aiso8 (S3 applies Winded : Removes and prevents Follow-Up attacks)
2.3.5 Black Widow Eiso8 (Martial Arts Combo gains Disadvantage)
2.3.6 Punisher Aiso8 (S4 Battle Van Adds Brutal Strike, Exploit Corruption and Attrition)
2.4.1 Emma Frost Eiso8 (Diamond Body no longer triggers Organic Recovery)
2.4.1 Magneto Eiso8 (Replaces Magnetized with Polarized, which cannot be removed or prevented)
2.4.2 Red Hulk Aiso8 (S4 Gamma Bomb grants 30% Heat)
2.4.2 Hulk (Reduces damage taken for each Hulk Up)
2.4.3 Valkyrie Aiso8 (Sacrificial Blessing has a 100% chance to apply Deathwatch to allies & becomes a QA)
2.4.3 Thor Aiso8 (S3 Inspire Bravery grants two stacks of Might of Mjolnir)
2.4.3 Enchanted Odin's Steel ( Deathbound : Grants Health to all allies when this enemy is KO'ed)
2.4.4 Cyclops Eiso8 (Provides Inspiring Leadership to all allies, increasing all stats)
2.4.4 Storm (Grants Protective Shroud to all allies at the start of combat)
2.4.6 Mockingbird Eiso8 (Mock Combat triggers before an enemy's attack)
2.5.1 Havok Aiso8 (Remove kick of mule)
2.5.1 She-Hulk Eiso8 (Gains Hulk Up each round, gains Hulk Up when attacked)
2.5.2 Ares Aiso8 (Personal apply disadvantage)
2.5.2 Kitty Eiso8 (Counter all attack with lockhead while not phased)
2.5.2 x-23 Eiso8 (Preemptively applies Trigger Scent when attacking if X-23 doesn't have Berserker Rage)
2.5.3 Invisible Woman Eiso8 (Party members with shields remove & prevent debuffs while shields r active)
2.5.3 Thing Eiso8 (Begins the fight with Stone Wall, Stone Wall reduces damage received)
2.5.4 Emma Aiso8 (Mind Control in s1)
2.5.4 Bishop Eiso8 (All Normal Actions generate 1 additional Potential Energy)
2.5.4 Havok Eiso8 (Protect allies from energy attack)
2.5.4 GEAR : Mind Control Weapon (Release all allies potential)
2.5.5 spira Aiso8 (Dance got multi-action)
2.5.5 Psylocke Eiso8 (Allies begin the fight with Mental Coordination)
2.5.6 GEAR:Hardened Wakandan Rungu (Exploits Shields, Staggered, Off-balance)
2.5.6 Hercules Aiso8 (Gift of Battle become QA)
2.5.6 Red Hulk (Begins the fight with 40% Heat)
2.5.6 Hulk Eiso8 (Chance to take reduced damage and resist crits from attacks)
2.5.6 She-hulk Aiso8 ( S1 Applies Hulk Up)
2.6.1 Vision Aiso8 (S2 •Infiltrator Interface grants Phased •Blaster Interface grants 5 stacks of Energy Charge)
2.6.1 Falcon Eiso8 (50% chance to avoid melee and ranged attacks)
2.6.2 Ghost Rider Eiso8 (First attack that would reduce GR's health to 0 will return him to 50%)
2.6.3 War Machine Eiso8 (Strategic Analysis also applies Disadvantage)
2.6.3 Iron Fist Aiso8 (Healing Chi and Praying Lotus Grant Rising Up)
2.6.3 Black Cat Aiso8 (Unlucky Strike applies Hexed)
2.6.4 Ghost Rider Aiso8 (Damnation Chains applies Sin to all enemies)
2.6.5 Punisher Eiso8 (When attacked, preemptively chances class to the attacker's counter-class)
2.6.5 Doctor Voodoo Aiso8 (S3 becomes a Quick Action but gains a shared cooldown)
2.6.6 Iron Fist Eiso8 (Combo Breaker has a 100% chance)
2.6.6 Rescue Aiso8 (Status Reset removes debuffs from all allies)
2.6.6 Deadpool Aiso8 (S1 applies Strengthened, Focused, Fortified, and Agile to both DP and the target)
2.7.1 Magik Eiso8 (Summoned Eyebites now apply Breakdown)
2.7.1 Omega Sentinel Eiso8 (Chance to gain the positive aspects of the target's class when attacked)
2.7.2 GEAR : Blind Rage (Cause allies to join in on single target attack)
2.7.2 Black Cat Eiso8 (Grant follow up attack on target which got bleeding)
2.7.3 GEAR : Devil's Fang (Bleeding, Woozy, Flanked)
2.7.3 Beast Eiso8 (Non-offense action get rehealth)
2.7.4 Hemdail Eiso8 (Chance to preemptively negate counter attacks)
2.7.5 Captain American Aiso1 (S1 applies Subdue - Melee attacks do 40% les damage & cannot crit)
2.7.6 Black Knight Eiso8 (Chance to block attack)
2.8.1 Bishop EISO8 (Gain potential energy when allies use energy attack)
2.8.1 Cable EISO8 (Psychic attack are guarantee to hit)
2.8.2 GEAR CHALLENGE : Vibra-Spear (Shield Breaker, Bleeding, Pressure Points)
2.8.2 Vision EISO8 (Increase chance to counter attack & become phased)
2.8.3 Molly EISO8 (Chance to eat leftover candy before her turn)
2.8.3 GEAR : Supernatural Side Arm (Disoriented x1 , Iso-8 Corruption x2)
2.8.4 Dr Strange AISO8 (Shield of the Seraphim now apply phased)
2.8.4 GEAR : Ring of Cyttorak (Debuff of Crimson Bands)
2.8.6 Kang EISO8 (Immune to Bleeding, Burning, Chilled, and Obsolete Tech)
2.8.6 GEAR : Gene Extractor (Genetic Sample, Disable)
2.8.6 GEAR CHALLENGE : Mental Manipulator (Manipulated, Weak Mind, Mind Control)
2.8.6 GEAR CHALLENGE : D1S-i5-5P4R7A (Depower)
2.8.6 Domino AISO8 (Aerodynamite gains Bleeding & Exhausted)

a) Mr Fantastic : Key point is to make Dr Doom fight with his clone
Default Tactician Suit is the preferable suit, and advised to filled with descent attack iso8

b) Hawkeye : Key point is his rapid fire passive buff
Modern Suit is the preferable suit, s4 on fake Hawkeye.

c) Phoenix : Key Point is s3 on Mini Boss, and equip with 20cp Empowered iso8
Default Tactician Suit is the preferable suit, and advised to filled with Health Recover iso8

Blue Pulverizing Augmented Iso-8 - 10Gold (Equipped Melee action applies Wide-Open) x23 & CB *Taking additional damage from melee attacks
Gold Pugilist Augmented Iso-8 - 10Gold (Equipped Unarmed attack gains Exploits Combos) QS
Red Vorpal Augmented Iso-8 - 15Gold (Equipped Slashing attack gains Ignore Defense) Beast s4
Blue Maddening Augmented Iso-8 - 5Gold (Equipped Psychic attack applies Weak Mind, increasing damage of Psychic attacks) Emma
Purple Sorcerous Augmented Iso-8 - 15Gold (Equipped Magic attack becomes Stealthy)
Green Gracious Augmented Iso-8 - 5Gold (Equipped Buff gains Energize, restoring Stamina to all allies)
Gold Powerful Blackbelt A-Iso - 30cp (Unarmed Increase Damage)
Blue Powerful Martial A-Iso - 30cp (Melee Increase Damage)
Purple Sniping Augmented Iso-8 - 10Gold (Equipped Gun attack gains Guaranteed Hit)

Best Heroic Augmented Isotope-8 :
S2 Mission 4.3 Epic (Thor)

New Best Character Restricted Iso:
The Hulk S2 Mission 4.2 (Reduces damage taken for each Hulk Up)
Mockingbird S2 Mission 4.6
Magneto S2 Mission 4.1 (Replaces Magnetized with Polarized, which cannot be removed or prevented)
Emma S2 Mission 4.1 (Diamond Body no longer triggers Organic Recovery)
Cyclops S2 Mission 4.4 (Provides Inspiring Leadership to all allies, increasing all stats)
Colossus S2 Mission 4.4 (Chance to counter single target and area attacks with S3 Decimate)
CapBritain S2 Mission 4.5
The Storm S2 Mission 4.4

Source:
http://avengersalliance.wikia.com/wiki/Augmented_Isotope-8

Are you talking about the incursion bug? I don't know all the details of it but from my understanding that if you refreshed during one of those fights it would give your account 5 gold each time. I don't think that it was just isolated to one country though and I've seen several pics of accounts in the 10K+ range of gold. As for PD doing anything about it I'm not sure and haven't heard anything.
I would expect them to do something but who knows they might treat it like the Angel or antidote bug depending on the number of people that got stuff from it.

great article written by Gareth Scott -

Things to consider when recruiting heroes:

Are they PvP top dogs?
- Consider getting heroes that will give you an edge in Player vs. Player tournament fights. Oftentimes, alternative uniforms play a part in unlocking a character's full potential. Examples of these characters are Quicksilver (Blue Costume), Emma Frost (Phoenix Five), Phoenix (White Crown), Psylocke, Captain Britain, War Machine (Iron Patriot), Magneto, Rescue, Union Jack, X-23, Wolverine (Brown-and-Tan) among many others.

Are they needed to unlock Spec Ops epic boss?
- The needed deployment heroes are usually composed of a previous PvP Tournament reward (in the next chapter, it should be Shatterstar), a new 90 CP hero, and a generally underused character.

Do they unlock premium missions?
- If your primary goal is to fully master the chapters, earn its rewards and unlock the premium missions, you may want to consider getting Hulk, Spider-Man, Wolverine, War Machine, Phoenix, Human Torch, Thor, Dr. Strange, Luke Cage, Captain America, Mr. Fantastic, Gambit and Scarlet Witch.

Do they unlock story epic bosses?
- Epic bosses are unlocked after all mission events are accomplished. These fights give the player a chance to win rare Agent gear. For this, you may need Black Cat (S1 2.3), Spider-Man (S1 3.5 and 7.3), Storm (S1 4.4), Wolverine (S1 5.3), Luke Cage (S1 6.3), Invisible Woman/Thing/Rogue (S1 9.4), Spider-Woman (S1 10.4), Phoenix (S1 11.3), Kitty Pryde (S1 12.2), Psylocke/Union Jack/Black Knight (S2 1.4), Rogue/Scarlet Witch/Spider-Woman (S2 1.6).

I am a new player. Who should I get?
- I say complete the roster of cheaper heroes before moving on to the higher tiers (90, 135 and 200). They may not provide as much utility as the more expensive characters, but they sure boost your PvP bonus stats at a dirt cheap price. Also, they help unlock future chapters that require an "X" amount of heroes.

Should I recruit 200 CP heroes, are they worth it?
- If you have the CPs to spend on them, why not? You never know if or when they are coming back to the store: Mockingbird, Emma Frost, Magik, Ghost Rider, Valkyrie, Havok, Hank Pym, Vision, Rescue, Wonder Man and Daimon Hellstrom. These heroes, however, are not required in any deployment, heroic battle, incursion, epic boss or premium mission events at the time of this writing.