The biggest problem I've found when either facing or playing with Deathstalkers is getting them to deal damage to the opponent. When you're playing all upped, odds are that your opponent will be playing with upped shields, many of which prevent at least 2 damage, thus rendering your Deathstalkers impotent. If you can work some Unstoppables into your deck instead I think you'll find they come into play much more often.