Rune Duelist

Defeat the 24-health sentinel by timing rune fusions and casts against its visible four-beat stance. Tap two adjacent identical runes to fuse them one level higher; select Cast mode and tap a rune to consume it. Red runes deal 2^level damage, blue grant that much persistent shield, green heal that much health (maximum 12). The sentinel cycles: Armor (red damage halved, attack 2), Wind-up (attack 3), Exposed (red damage doubled, attack 0), Slam (attack 5). Every successful fusion or cast advances one beat and triggers that beat’s counterattack, unless the sentinel was defeated. Selection and mode changes are free. Each beat adds the next visible level-1 rune to the first empty cell. You have twelve beats. Fuse before an exposed window, but cast shield before taking a heavy hit. Keyboard: Tab and Enter/Space operate buttons; R restarts.