When a Magister riding the Doom Bell chooses targets for Spells with Type: Direct, it ignores the restriction of only choosing targets in the Front Arc.
When a Magister riding the Doom Bell chooses targets for a Spells with Type: Missile, it can draw Line of Sight in 360o (from any point of the Doom Bell’s base) and may cast Missile Spells even when Engaged in Combat.