Act 5.4.6 has Classic Ultron (OG Ultron) boss to fight. What makes this fight different is aggressive regeneration, power gain, and other buffs. Every time one buff will show up there, but it will not get activated unless you put a debuff on Ultron. Even if you use parry, that buff will activate. If it is a power gain buff, you are likely to get killed as Ultron will get Level 3 Special bar filled.
What are the Best Champs to use against Act 5.4.6 Boss Classic Ultron
Megneto (Red)
Void
Spam L1 to reverse Regeneration to Degeneration and it will also help you to stop the power gain. Void is one of the best counters for the fastest killing. Don’t rush to hit him and do damage, just try to reverse his healing and also hit block whenever you can so that you don’t get cornered.
3-star Void vs Ultron 5.4.6 Boss
Captain America Infinity War with Tech Synergy
Captain America IW must be duped, the higher signature he has, the better it is. Tech synergy applies petrify debuff with each parry that prevents regeneration. I am also using Depair Mastery that reverses the regeneration effect and helps to kill Ultron Faster.
What to do: Just look at the regeneration buffs and parry to make a regeneration buff trigger and then try to stack more petrify debuffs by parrying. The objective is not to beat him by hitting but by reversing his regeneration only.
3-star Captain America IW vs Act 5.4.6 Ultron
White Magneto
White Magneto also gets 70% ability accuracy against Metal Defenders, so he should do it easy as well.
Loki
Loki’s Curse and Buff steal is the key to winning. Try getting L3 filled and use it to set a curse on Ultron. Loki will steam all buffs as long as Ultron is under the curse. You can use a Heavy attack to reset the curse timer: Just Parry and use Heavy. Once Loki Steals the Fury Buff, he will hit like Ultron and kill him quicker than any other champ.
Beating Ultron 5.4.6 Boss With 3-Star, 4-Star, and 5-Star Loki
Medusa
Medusa armor shatter will help you win. Once the Ultron’s Armor is shattered, his regeneration and Power gain will stop, and he will take more damage.
4-Star Medusa vs Ultron 5.4.6 Boss
Star-Lord
Just don’t lose the combo and Ultron will be dead very fast. SL must be duped, though.
Nebula
Get 5 charges and then Ultron will not gain any buff. She will reduce its ability accuracy by 100%. However, you will have to intercept. If you parry Ultron, make sure you get those 5 charges first before you intercept again. She may take a little longer because she doesn’t hit hard enough, but she will do the job.
Vision Arkus
He can break armor, apply cold snap and shatter armor with Special 2. After the armor is shattered, Ultron will not gain any power (not even from attack). Coldsnap will also disable its evade. However, try to stay away (don’t break armor or apply coldsnap) when he has power gain buff in rotation, and armor shatter is not applied.
Scarlet Witch
Scarlet Witch has various abilities, like Nullify, Power Lock, Power Gain, etc. Her L2 does a ton of damage. I have seen almost 50K Damage with her L2. So she makes it very easy to fight as long as you don’t get hit.
Scarlet Witch vs Ultron 5.4.6 Boss
Doctor Doom
He can steal power and a duped Doctor doom can also steam power gain. He can also apply a stagger to nullify the next debuff and can nullify buffs with Special 1.
Iceman
Iceman is immune to bleed and poison, so if a slip-up happens, it will not kill him. Iceman starts a fight with Cold Snap and you can again set a cold snap with L1 or L3. Ultron cannot evade under the effect of Cold Snap that will make him easier to fight. However, this fight will take a little longer.
Quake
Quake is also great if you know how to play her. She can kill Ultron without a hit.
Hyperion or any hard hitter champion
Hyperion hits hard enough and can help you finish the fight fast enough. However, it will require lots of intercepting skills.