Top Swap gives predictability in access to Instant/Sorcery, so this card rewards you for having storm-ish turns. You can always throw it out there as the end cap to a turn, knowing you'll draw it again next turn. Scales with how many spells you were able to play.

This has to be considered in the space where you have two copies; in that case you could cast this as many times as you have cards in hand, continually getting little fighters. That's probably fine..? It could be that things with this mechanic need to cost 2+ in order to reduce their use as combo pieces.