"Use when you declare an attack targeting a hostile figure with the highest figure cost of all hostile figures on the map. You become Focused and apply +1 [Damage] to the attack results."
Is the requirement exclusive? Was playing yesterday and opponent had 2x Repulser Tanks at 10 (none higher). Can I use this on the Repulser Tank while both are alive? Or do I have to wait until one is dead and then use it on the other?