The above cards would play out like this: on turn 3, if there are not enough creatures worth killing on the opponent’s board, cycle it at the end of your opponent’s turn. Regardless, before you drop Dark-Dwellers, play out Soul-Scar if necessary. Use Dark-Dwellers to replay Sweltering Suns and wipe your opponent’s board now that it’s developed. If they had a beefy battlefield of beaters, Soul-Scar can be used to great effect, shrinking everything down to size. If you’ve the mana, why not precede this with a handy [c]Shock[/c] so Soul-Scar survives the encounter?