Sonar Strike

Four damage at instant speed for two mana would overreach on an unconditional white removal spell, so the effect is gated to creatures that have already committed: those attacking, blocking, or tapped. You cannot point it at an untapped blocker holding back, and you cannot use it proactively to clear a mana dork before it swings or taps. That restriction turns it into a combat-decision tool rather than open-ended removal: it answers the creature that swings into you, kills a blocker mid-combat, and mops up whatever tapped for value or attacked last turn and did not untap. White has long paid for cheap creature removal with exactly this kind of conditional targeting (spells that only hit attackers, or only tapped things, or demand a creature you control), because unconditional white kill is a color-pie boundary the game guards carefully. The three life is a tribal rider, live only when you control a Bat, and it is deliberately weightless: the card functions identically without it, so the lifegain reads as a reward for a build rather than a reason to run the card. That separation is good discipline. The removal stands on its own for anyone who wants a two-mana combat answer, and the bonus tilts it toward a specific tribal shell without holding the base effect hostage to it.