Before the game starts, but after Scouts have been deployed, a Lustrian blot toad marker can be placed for each unit of Ripperdactyl Riders in your army. A single blot toad marker can be placed on any enemy unit on the tabletop, this marker remains throughout the battle.
When fighting in close combat against a unit with a blot toad marker, the Ripperdactyl's Frenzy grants it D3+1 extra Attacks, instead of just 1 (roll once for the whole unit) and the Ripperdactyls re-roll all failed To Hit rolls.