Paper Phrog

Paper Phrog is an Ironclad-only relic that raises Vulnerable's damage multiplier from 50% to 75%. Decks that reliably apply Vulnerable see every Attack gain a further damage bump. The cumulative effect across a run is larger than the number suggests.

However, Vulnerable typically expires after 2 turns, and maintaining it continuously requires enough Vulnerable-applying cards and draw. On turns you can't apply it, the relic does nothing, so skipping is a reasonable option when your deck lacks Vulnerable tools. The rating of this Uncommon relic swings heavily based on deck context.