Yes, you can burst them. However, I would strongly advise you to save your money and runes for something else. The slayer tower is single combat, so despite those spells being multi combat spells that can hit multiple targets at once, you can only fight one nechryael at a time. The slayer tower is much better if you are going to kill Nechryaels with melee.  This is going to be a lot slower than using melee. If you want to burst these monsters, you will have a much better time just going to the catacombs of Kourend and fight them there with ancient magic. This is a multi combat zone, and you can attack up to 8 at a time there.  The drops there are also very good. If you burst them with ice burst, you will almost always have a pretty decent profit at the end of your task. If you barrage them you might have a slight loss or you will break even depending on how concentrated you are and which drops you pick up.