Guide:Cryogen strategies

Cryogen is usually the first Hardmode boss that players will face in their playthrough. Cryogen will inflict debuffs that hinder movement speed, such as Chilled and Glacial State. It will transition through six phases based on its current health, the final phase often being considered the most difficult, with Cryogen ramming the player at very high speeds. Cryogen is summoned by using a Cryo Key in the Snow biome at any time.

This guide will mention items exclusive to Expert and Revengeance Mode with no special formatting and will follow the intended progression.

Terrain Preparation
Staying in the Snow biome is highly recommended, as Cryogen will enrage and gain a speed boost if it leaves the Snow biome. An arena with actuated snow/ice blocks will extend your Snow biome.

Build a long set of two to three platforms and level the ground of the arena to act as a fourth layer. Place the platforms around 20 blocks apart. Great vertical and horizontal mobility is a must for this fight, considering the high mobility of the boss itself. Cryogen will not get stuck on platforms, nor will its summons. Campfires and Heart Lanterns are useful assets to boost your health regeneration, so they should be placed throughout the whole arena.

During the fight, Cryogen will summon Cryocores, and Aurora Spirits that will interrupt the fight, so keep this in mind when building arenas.

The bottom layer of the arena can be built with Ice Blocks, increasing the player's acceleration and top speed, both of which are useful assets in the fight (provided the player is equipped with Frostspark Boots). However, this is not necessary.

Armor

 * Titanium armor is generally the preferred choice for almost all classes.
 * Palladium armor can be good for its regeneration boost, which gives it a better suvivability than Titanium due to the nerfs to this armor.
 * Spider armor is best for Summoners as its additional minion damage is better than the Statigel's additional slime minion.
 * The Forbidden Circlet offers fairly weak damage boosts but a strong set bonus ability that can shred the boss if it lands.
 * Titan Heart armor should be utilized by rogues who prioritize on Stealth Strikes.
 * Frost armor grants medium bonuses to melee and ranged damage and critical strike chance.

Accessories

 * Frozen Wings are extremely useful in general, and should be prioritized.
 * The Aero Stone, Grand Gelatin, or Frog Leg will improve the usefulness of wings even further and improve vertical motion.
 * Frostspark Boots or their predecessor, Lightning Boots, are a necessity to keep up with Cryogen.
 * The Evasion Scarf or the Shield of Cthulhu allows the player to make sharp turns and are equally as useful as the previous accessories. They should always be a part of the player's arsenal when fighting this boss.
 * The Worm Scarf will boost the player's damage reduction. However, Melee players might opt to use the Bloody Worm Scarf due to the increase in stats it provides.
 * If getting hit disrupts your rhythm in the fight, the Ankh Shield or the Cross Necklace and its upgrades will allow you to more smoothly recover in case of a mistake.
 * Using your class specific emblem is highly recommended for an extra boost of damage. Note that Calamity also has an exclusive emblem for the Rogue class.
 * The Magic Quiver works well in maintaining ammo as well as greatly improving the firepower of bows, but it is not required.
 * Magic players can make use of the Celestial Cuffs and/or Mana Flower along with Mana Potions to recover their mana during the fight, as well as using the Mana Polarizer to recover lost health.
 * Summoners can boost their minion damage and defensive stats with the Spirit Glyph.
 * Rogue users will find the Raider's Talisman useful to boost their damage output.

Weapons
The weapons from Biome Mimics or the buffed Sunken Sea are great options for the fight along with many other options early Hardmode has to offer. Using class specific Abyss weapons can work against Cryogen, although many other options are available that are more effective. Homing weapons, or weapons whose projectiles move quickly are very effective as Cryogen moves very erratically in its later stages, especially in Revengeance or Death Mode.

It is sometimes preferable to fight the other bosses at this tier in progression to have a much wider array of options, some of which are listed below.

Melee

 * The Storm Saber is an efficient and quick option for Cryogen.
 * The Axe of Purity's right click attack is considerably easy to use and is rather effective for this fight.
 * The Eutrophic Scimitar is a slow but powerful option and its electric bolts can briefly stun Cryogen's minions.
 * The Clam Crusher is another slow and powerful option that requires smart use of gravity in order to deal great damage.
 * The Yin-Yo is an excellent option for players looking to use yoyos.
 * Fetid Baghnakhs are a true melee option that can decimate Cryogen, at the cost of having to be close to the boss.
 * The Ark of the Ancients is an extremely powerful sword that will tear through Cryogen.
 * The Celestial Claymore is a very effective option for when Cryogen reaches low HP.

Ranged

 * The Flarewing Bow can decimate Cryogen, best used with Ichor Arrows.
 * The Dart Pistol paired with Cursed Darts can grind Cryogen swiftly.
 * The Butcher can deal massive damage to Cryogen, but it requires the user to charge up fully before it can reach its full potential.
 * The Onyx Blaster combined with Ichor Bullets can quickly deal with Cryogen.
 * The Archerfish's piercing abilities, good rate of fire and damage all prove to be incredibly useful during the fight, allowing the player to hit multiple entities at the same time.
 * The Uzi is a good alternative to the Archerfish. Although it might lack piercing, it deals higher base damage and allows for special bullet effects like that of Crystal Bullets.
 * The Slag Magnum is another good option for Cryogen as it inflicts Armor Crunch on hit.
 * The Clamor Rifle is a good option; trading DPS for homing capabilities.
 * The Arbalest (RIV) is extremely good for this fight, however its rarity may make it difficult to obtain.
 * The Sea's Searing (Legendary) is an option that completely controls the fight, from the boss to its summons. However, it may be difficult to obtain due to its rarity.

Mage

 * The Frigidflash Bolt is an excellent option due to its high DPS and its piercing. Note that this drains mana very quickly, so always have Mana Potions at hand.
 * Serpentine is a very powerful option when combined with armor penetration from the Deific Amulet.
 * The Relic of Ruin is a powerful magic weapon that can effectively deal great damage to Cryogen while allowing the player to focus on dodging because of its homing ability.
 * The Meteor Staff is another very powerful option that is easy to land hits with when Cryogen is towards the top of the player's screen.
 * The Black Anurian is usually a good choice, but is outclassed in some situations by other magic weapons at this point.
 * The Crystal Serpent and the Sky Fracture are good choices, providing accuracy and high damage.
 * The Crystal Storm will make quick work of the ice shield.
 * The Laser Rifle's fast-moving projectiles make it easy to use and can deal large amounts of damage.
 * It’s highly recommended that players use the Golden Shower to inflict ichor.

Summoner

 * The Black Hawk Remote's Black Hawks and their projectiles are good for directly hitting Cryogen and is especially useful when Cryogen enters its final phase and should be prioritized.
 * The Ancient Ice Chunk's Ice Claspers are excellent for crowd control, but they will have a hard time hitting Cryogen during the last two phases due to Cryogen's speed.
 * The Forgotten Apex Wand is a good option with its high damage.
 * The Shellfish Staff is a secondary option that has more DPS than the Ice Claspers but with terrible crowd control.
 * The Tavernkeep Rods can be used for extra firepower, especially against the minions spawned by Cryogen.
 * The Queen Spider Staff can also be used for the same effect.
 * The Caustic Staff can be used for debuffing Cryogen with several different effects.

Rogue

 * The Gacruxian Mollusk is an extremely powerful option, making quick work of Cryogen.
 * The Prismalline is an excellent option for Rogue users as it is non-consumable with good DPS and excellent crowd control. To maximize DPS, the daggers should split right before hitting Cryogen.
 * The Lionfish is a great option for Rogue users thanks to its non-consumable nature, as well as it being very simple to use.
 * The Spear of Paleolith is another good option, as it inflicts Armor Crunch, a very powerful debuff.
 * The Spear of Destiny (RIV) is extremely powerful due to its homing, however it may be difficult to obtain because of its rarity.
 * The Blast Barrel can kill Cryogen in a minute or less if you bounce it against walls so when it levels with you, the flares will destroy it.

Classless

 * The Golden Gun and the Lunic Eye are two extremely useful support weapons that will make the fight considerably easier.

Miscellaneous

 * The Well Fed buff provides a useful all around stat boost.
 * Farm Blood Orbs to easily craft many helpful potions that will increase your survivability.
 * Every potion available can be crafted with Blood Orbs, so use this to your advantage. Many potions craftable with Blood Orbs are not normally accessible before the player fights Cryogen.
 * Melee and Rogue players should utilize flasks crafted at an Imbuing Station to inflict powerful debuffs without the need to change to other weapons.
 * The Warmth Potion is buffed in the Calamity Mod, and will make you immune to almost all debuffs that Cryogen inflicts along with reducing the damage Cryogen gives.

The Fight
Cryogen will spawn off-screen, which means the player should be prepared to dodge projectiles that Cryogen fires as it approaches them. For the first four phases, Cryogen will occasionally spawn an ice shield around it that must be destroyed in order for Cryogen to take damage again. Cryogen will also periodically fire frost bolts at the player during most phases. Cryogen will spawn minions to disrupt the player, make sure to take care of them on all difficulties. Circle Cryogen for the first phase. Using platforms to help reset wing time/jumps is very useful.

When phase two begins, Cryogen will attempt to move above the player. Strafe slowly and continuously left or right, while continuing to deal damage with projectile based weapons. Letting Cryogen get above the player will cause Cryogen to rapidly fire ice shards similar to The Perforators' blood rain, inflicting Glacial State, which is almost a guaranteed death on higher difficulties. To avoid these, run just below Cryogen until the ice shards come into view, then dash in the opposite direction.

Cryogen will begin to level itself with the player in phase three. It will fire ice shards in bursts that will rain down after traveling a short distance. Picking up pace while strafing around it helps to avoid these. Use a Rod of Discord to avoid Cryogen while turning around.

Phase four is very similar to phase two, except Cryogen loses the ability to fire frost bolts. In exchange, it fires ice shards at an increased rate. Don’t slow down during this phase.

Phase five will cause Cryogen to lose the ability to regenerate its ice shield and the ability to fire ice shards. Instead, Cryogen will fire frost bolts again, albeit more rapidly than other phases. It also teleports every few seconds around the player, making timing Rage and Adrenaline extremely difficult. Slowing strafes down helps to avoid colliding with Cryogen as it teleports.

Phase six will cause Cryogen to lose all other abilities, but gain a speed boost as it tries to ram into the player at high speeds. Cryogen will also occasionally charge off-screen, so using the minimap to track its movement is very effective. Try to start this phase on the top platform and dodge Cryogen by timing a circle around it. If Cryogen is above the player, fly up and use a dashing accessory to dash in the direction of Cryogen when it begins its charge. If Cryogen is below you, hop down and dash towards it. Continue this for the rest of the Phase until Cryogen is defeated.

General Tips

 * The Rod of Discord can help the player get out of sticky situations.