Does Lux legend's ability trigger to draw a card when a spell (Falling Comet) is cast but has no legal targets when it tries to resolve?

Ruling: Yes, Lux draws a card. The spell was played and resolved (to no effect due to lack of legal targets), which triggers Lux's ability.

Sequence:

• Spell is cast
• Spell attempts to resolve
• Spell resolves to no effect (no legal targets)
• Lux's ability triggers and draws a card

Nuances:

• A spell that resolves to no effect is still considered "played"
• If a spell is countered, it would NOT be considered played and would not trigger the draw
• "Played" means the spell resolved, not just that it was cast