Spot Weakness

Spot Weakness is a 1-Energy Ironclad skill that grants 3 permanent Strength (5 upgraded) if the current enemy intends to attack. Strength gained this way persists for the rest of combat and stacks with other Strength sources. When the condition is met — which is most turns in most fights — Spot Weakness is among the best Strength-gaining cards available: 3 Strength for 1 Energy is efficient without any downside.

The conditional nature is the only caveat: against enemies that aren't attacking on a given turn (e.g., while buffing or summoning), Spot Weakness gives nothing. But since most enemies attack most turns, this rarely matters in practice. Upgraded at 5 Strength, it's an extraordinary Strength source and a natural fit in any damage-scaling Ironclad build.