In activities like nightfalls (Cerberus Vae in particular as it never seems to have nightfall burns) it is absolutely paramount in killing enemies at a safe distance. Never needs ammo, just patience and time (should have swapped the names at the developer meeting). On a side note it only has 6 shots, swapping to another weapon reduces your ammo by half for your new gun. However this is done in percentages. 6 shots on ice breaker is 100%. If you swap it for a sniper that has 24 for example you will get 50% max ammo ergo 12. Very useful when you either don't have synths or it's on cooldown. You can regenerate ammo for other weapons 2-3 times for every 5 minute synth cooldown. These are all things that make icebreaker an excellent weapon to have.