Screamers are made for bombers mostly or SHF that can fire 2 mines at once ( you drop one screamer and one nuke and if they hit they'll make ez. hull dammage) . If you fight a bomber into a snipping way ( 1 shoot SNAC ) Screamers allows you to deshield faster your target, but also kills power core. So if you know your target is also trying to snip your ship, hitting his hull with a screamer will give you the opportunity to aim a SNAC twice right before he does (taking into account he uses the same tactic)