Beamsplitter Mage

The copy is created on the stack, so it’s not cast. Abilities that trigger when a player casts a spell (like Beamsplitter Mage’s ability itself) won’t trigger.

In some rare cases, the original spell can target another creature but the copy can’t (most likely because an effect modified the characteristics of the original spell on the stack and won’t modify the copy). If the copy can’t target the chosen creature, the copy isn’t created.

If you copy a spell, you control the copy. It will resolve before the original spell does.

The controller of a copy can’t choose to pay any alternative or additional costs for the copy. However, effects based on any alternative or additional costs that were paid for the original spell are copied as though those same costs were paid for the copy.

If you don’t control another creature the spell could target as Beamsplitter Mage’s triggered ability resolves, you don’t copy that spell.