Arknights: In-depth Review - Corroserum

Corroserum is the future 5★ Blast Caster featured in the Path of Radiant banner, which will run alongside the Near Light event. This archetype used to be the longest-running one without a second Operator, having featured only Ifrit from release up to 2.5 years after the game came out. Still, Ifrit’s incredible kit solidified it as an incredibly strong option for Arts damage, pairing excellent damage with debuffs and a really useful range. Can Corroserum carry that torch? Let’s find out!

Some of the most important factors about Blast Casters are innate to the archetype, such as their incredibly long range and true AoE damage, giving them an edge over regular Splash Casters. In this regard, Corroserum still performs about as well as you’d expect, but as we will see later his insanely high cost (one of the highest in the game, in fact) may not be worth it for the support he can bring to the party.

Where Ifrit focuses on heavy damage paired with powerful debuffs, Corroserum instead opts for somewhat lower damage (as expected from his lower rarity) with Silence support. Let’s see how this translates into his stats!

Corroserum’s stat spread is generally just a worse version of Ifrit’s, who beats him even at equal levels. Every single one of Corroserum’s stats is lower than the aforementioned Blast Caster (save for his DP cost), but what really hurts the worst is his Attack stat.

Even at equal levels, Corroserum loses against Ifrit in the Attack department by over 100 points, which is a pretty huge deal when your archetype is heavily DPS oriented. We will see how this impacts his viability later, but for now let’s look at his Talent.

After not attacking for over 4 seconds, Corroserum’s SP regeneration increases by 0.45 per second (+0.05 at P5).

This is a pretty decent boost for stages where the enemies come in waves and not in a constant stream, and synergizes pretty well with one of his skills (the one that makes him a worse Ifrit). It also stacks with other SP boosters, such as Ptilopsis or Mostima, resulting in potentially really quick charges.

In comparison to Ifrit’s second Talent, this one gives potentially quicker charges, at the cost of the consistency that Talent offers.

When activated, this skill immediately grants Corroserum a massive 135% Attack boost for 30 seconds, but he is stunned for 10 seconds after the Skill ends.

While the stun at the end of the Skill would usually be considered a negative aspect, Corroserum’s Talent makes it so that over half of that time is spent recovering 45% more SP every second (50% at P5). This quickens his downtime from 30 seconds on the first cast to a little over 27 seconds under the worst possible circumstances.

This, however, is not enough to save Corroserum’s DPS in comparison to other Operators: Ifrit’s much higher Attack single handedly sweeps the floor with him in regards to both Average and Burst DPS with her second skill, Pyroclasm, and suffers much less from Resistance increases due to her Talents. He even struggles to compete with peers of his same rarity, with Skills like Leonhardt’s Deconstruct and Detonate having much better Burst DPS with similarly strong Averages, unrestrained by the Blast Caster’s range. His Resistance debuffs also let him fare better against Resistance.

In the end, despite being Corroserum’s strongest DPS Skill, this one fails to be impactful enough to warrant the huge Deployment Cost he needs. It has neither the damage nor the utility to rival similar Operators, and should only be used as a last resort.

When activated, this 25 second long Skill boosts Corroserum Attack by 100%, and his attacks silence all targets hit for 5 seconds.

This skill trades a significant amount of Corroserum's firepower for a more support-oriented presence, giving him some of the longest Silence infliction capabilities in the game, second only to Lappland and Jaye’s Shell Splitter. However, his uptime is not that great (38% if his Talent does not trigger), and the mediocre damage he can output doesn’t make up for it against enemies that need to be killed quickly, at least not in comparison to other options.

This also doesn’t mix well with his range and very slow Attack Interval, forcing him into conventional “Ifrit lane” positions where he is able to Silence enemies before they enter another Operator’s range. At that point one may as well use another long-ranged Operator with easier positioning.

In the end, Silence is a pretty poor debuff to have for a Blast Caster due to the limitations this imposes on their map placement, cutting a significant amount of desirable positions. Compounded with the fact that Silence usage is also limited by the enemy composition of specific maps, Corroserum ends up with a strange niche of AoE Silence that, while he is the only that can accomplish it, ends up being rather poor.

So, should I pull for Corroserum? Is he as unbelievably broken as Ifrit is? Does his high-range AoE Silence carve a good niche for him? The answer is NO. Corroserum struggles with a pretty inadequate mix of archetype and kit which makes him an inferior choice to Operators with better damage or better ways to pick off enemies you would like to Silence. Even though most people pulling for Nearl the Radiant Knight will likely get him, he will not be an incredibly good addition to most people’s roster.