Can I play Lucian's signature spell (Relentless Pursuit) if I have no equipment in play?

Ruling: No, you cannot play Relentless Pursuit without controlling an equipment. You must choose both a friendly unit and an equipment you control when casting the spell, even though attaching the equipment is optional.

Sequence:

• Choose both a friendly unit and an equipment you control as the spell is cast
• Move the chosen unit
• You may choose to attach the chosen equipment to that unit
• The unit gains "When I conquer, you may move me to my base" until end of turn

Nuances:

• The equipment must exist to cast the spell, but attaching it during resolution is optional
• This is a special case where the card text creates a targeting requirement despite using "may" language for the attachment
• The unit still moves and gains the conquest ability even if you choose not to attach the equipment