I've had this idea for buffing Juggernaut scrambling around in my head for a while, but then he got buffed by Kabam before I got to writing it down. Since I didn't just want to throw it away but also didn't want to rebuff Juggernaut since he seems to be pretty cool after the latest update, I decided to rework the buff idea for Unstoppable Colossus instead.

Signature Ability

When afflicted by reverse controls, gain 4000 Physical Resistance and an Unstoppable Buff for the duration of the effect.

When hitting into the opponent's Block during Special Attacks, the last hit is Unblockable. Unless the opponent has Class Advantage, it also passively Stuns them for 1 second.

If the opponent is under the effect of a Power Gain Buff while Power-Locked, convert the Power Lock into a Power Burn instead. Additionally, Unstoppable Colossus's Power Burn effects can't have either their potency or duration reduced by Cosmic champions.

Note: A lot in his kit is geared toward countering Vision (Aarkus) because I find him to be an annoying defender. Case in point: passive stuns after special attacks that hit into block (more on that later) and power manipulating effects that can't be resisted by cosmic champs.

Passive

Immune to Bleed and Armor Shatter, as well as 100% resistant to Coldsnap, Frostbite and Rupture.

The opponent's Combat Power Rate is reduced by 35% when above 1 Bar of Power.

If Unstoppable Colossus' Ability Accuracy is below 100%, the opponent's Combat Power Rate is reduced by a further 50% when above 2 Bars of Power.

Note: Not much to say here. I mostly kept OG Colossus' own immunities but changed some of them to resistances, as well as swapped incinerate for rupture. He still doesn't take any coldsnap damage because screw Aarkus. I also changed OG Colossus' ability that gives him increased power gain when below 100% ability accuracy to one that's suppressing the opponent's power gain instead.

Always Active

Whenever Unstoppable Colossus crosses a Bar of Power, he gains an indefinite Armor Up Buff. Max 10. He is unable to gain any indefinite Armor Up Buffs while under the effect of Slow.

Whenever the opponent crosses a Bar of Power, Unstoppable Colossus gains an additional Armor Up Buff for 8 seconds. This duration is halved if he is under the effect of Slow.

The potency of Armor Break Debuffs applied to Unstoppable Colossus is reduced by 100%. If a Cosmic champion removes one of Unstoppable Colossus' Armor Ups through any means, replace it with an Armor Up passive with 115% potency for 8 seconds.

Whenever Unstoppable Colossus is under the effect of an Armor Up passive, all of his Unstoppable attacks are also passively Unblockable.

Note: The main engine for his kit. Don't try to remove his armor up buffs if you're a cosmic champion. That won't work and it'll be a bad time. However, they are still very manageable for science champions with access to slow.

When Dashing Forward

Convert an Armor Up Buff into an Unstoppable Buff for the duration of the dash. If he is Unblockable during this attack and breaks the opponent's Block, his Armor Up Buff is refunded.

Note: Instead of going unstoppable after special attacks, Unstoppable Colossus can now live up to his name and be unstoppable a lot more frequently by using his armor up buffs as fuel for his momentum. You just got to be somewhat careful so as to not run out of armor up buffs.

Heavy Attacks

Staggers the opponent for 9 seconds and reduces their chance to activate Unstoppable effects by 100% until they cross their next Bar of Power.

Converts up to 5 of Unstoppable Colossus' Armor Up Buffs to Power Lock the opponent for 1 second per Buff converted.

Note: I hate being unstoppable while the opponent is as well. That takes away a lot of the charm. With Unstoppable Colossus, you don't have to worry about it. Apart from placing a general stagger on his opponent, he also shuts down their ability to trigger unstoppable effects themselves until the next time they cross a bar of power. Couple that with his ability to lower their combat power rate significantly and you can keep them quite stoppable for long stretches of time.

Additionally, the heavy attack locks any annoying power gains in place. If the opponent has any power gain buffs active while this power lock is in place (AARKUS!), his sig will deal damage to them as well by converting the power lock into a power burn.

Special Attack 1

Inflict the opponent with a Buff Suppression passive that Power Burns 10% of their Max Power every time they activate a Buff for the next 8 seconds. Every time an Armor Up Buff on Unstoppable Colossus expires, pause the Buff Suppression passive for 2 seconds.

Note: If you don't care about keeping your opponent's buffs in check, you can instead use them to your advantage by burning their power every time they gain a new buff.

Special Attack 2

The first hit transfers any Armor Breaks currently active on Unstoppable Colossus to the opponent with 200% potency for the duration of the attack. Each additional hit of the Special Attack inflicts the opponent with a stacking indefinite Armor Break. Max 30.

If the first hit strikes the opponent's Block, go Unstoppable and gain 750 Block Penetration for each Armor Up effect for the duration of the Special Attack. Gain 70% of the damage done through Block as health over 2 seconds.

Note: The first paragraph will be the bread and butter when it comes to his damage build-up. Stack those armor breaks, then launch an SP3 for a big payoff. The second paragraph is more of a safety net if you mistime the special, or if you have a difficult opponent that is just turtling on you. With the signature ability, the last hit will also break through the block and stun the opponent in order to ensure that you don't get retaliated against immediately.

Special Attack 3

Converts all Armor Breaks on the opponent into Degeneration passives, each dealing 2300 damage over 18 seconds.

While his opponent is under the effect of Degeneration, Unstoppable Colossus's Combat Power Rate is increased by 25% and his Special Attack damage is increased by 20% per Armor Up Buff on him.

Note: The degeneration will do a fair amount of damage, but just as important is the long boost it gives your power rate and special attack damage. Use it to build up additional armor breaks on your opponent ahead of a new SP3.

Synergies

Unstoppable Force (Juggernaut):
Basic attacks have a 15% chance to shrug off non-damaging Debuffs.

Unmovable Object (Colossus):
Colossus places a Stagger on Cosmic champions for 8 seconds every time they fail to inflict an Armor Break on him.

Unstoppaball Special (Wolverine, Old Man Logan):
Go unstoppable for 2 seconds when activating a Special Attack against a Cosmic champion.

Sestra (Magik):
Power Burn 10% of the opponent's Max Power every time you Nullify a Buff.

Note: Nothing too special. I don't have a Juggernaut so I had a hard time coming up with a useful synergy for him since I haven't had the chance to test out his new buff, but I thought it could be useful to be able to shrug off non-damaging debuffs since all of them shut down his Gem of Cyttorak.