This skill is a Special Rule that is only available to specific Star Players. Please visit this page to find a list of current Blood Bowl Star Players.
Dwarven Scourge
Once per game, when an opposition player is Knocked Down as a result of a Block action performed by Ivan, you may apply an additional +1 modifier to the Armour roll or Injury roll. If this is against a Dwarfen player from any team, this may instead be a +2 modifier.
Dwarven Scourge is very similar to some of the existing star player special rules and is quite straight forward to use. Like those others I’d recommend just using it the first time you break the armour on an opposing player as it gives you the best chance of removing an opponent.
You could perhaps also use it if it’s the extra +1 you need to break the armour on a particularly valuable or troublesome opponent.
The +2 ability against dwarven players is going to be very situational. The obvious times it will come into play is if you are facing off against either a Dwarf or Chaos Dwarf team. There are also some Dwarven players on Old World Alliance teams, though as there are less of them, there’s a greater chance you may not be hitting them, or get an armour or injury roll where this ability comes into play.
Lastly there’s the even slimmer chance that you might be up against a Dwarven star player. Again this makes it even less likely that it will come into play, unless perhaps you are focusing your efforts with Ivan against that one player. Generally though I don’t think that’s likely to be a great idea and may actually hamper your own team’s gameplay.
Are Chaos Dwarf’s a “Dwarven team” ?
It’s done on a per player basis rather than per team. For example Hobgoblins are not Dwarven players. However a Chaos Dwarf Blocker is.
Bull Centaurs are up for debate right now, they aren’t listed as “Chaos Dwarf” Bull Centaurs.
It would also include Dwarven Star Players. Previous Star Player cards had keywords on them such as “Human Blitzer” etc but it looks like the second season redesign has removed these.
It wouldn’t surprise me to see a list of applicable players added to the FAQ at some point, if this happens I’ll try to remember to update this article with the list.