Castle Radion is a great milestone for Airoheart players since they get their first ranged weapon: the crossbow. This allows players to slay enemies from a safe distance. Hopefully, they've been working on their aim because you can't defeat the boss of this area without some very precise arrows.
Projectile-heavy boss in Castle Radion
The second boss players need to slay in Airoheart is one huge eyeball (looks very similar to Phantoon from Super Metroid. Once the fight begins, the boss will summon a smaller eyeball to encircle the boss, shooting a projectile at the player. This projectile cannot be blocked with the shield
If the player manages to eliminate the smaller eyeball, there will be a small window where the player can shoot arrows at the boss' eye. This window is pretty small, though, and the boss will use this time to charge up a large green beam. Players should normally be able to get four shots before needing to roll to the side.
Related: How do items work in Airoheart?
As the boss takes more damage, it will summon a second smaller eyeball, a third, and later a fourth. Only one smaller eyeball can shoot the player at one time, though. Since the player needs arrows to hurt the boss, it's better to use the sword to cut down the eyeballs if possible.
This strategy is a bit riskier, but it's often better to just take the damage if it means getting rid of an eyeball (they go down in two sword strikes). There are four arrow refills at the bottom of the room, but that's it; once that's exhausting, the player can't get any more arrows to shoot at the boss.
At the top of the room are pots with hearts, including one with a green potion. The easiest way to deal with this boss is to cut the small eyeballs with the sword and shoot at the boss with arrows. If the player takes damage, they can always refill their health with the hearts and potion available.
Want more Airoheart guides? Pro Game Guides has you covered with Airoheart - how to access the full map.