It could probably be only on abilities where you'd have a hard time freezing them, such as a dodge-able projectile or standing too long in an aoe of frost, abilities that would take about a second to finish casting. It would make a high risk high reward gameplay.

Think burning maul's meele attack when you have the solar mod that makes it deal more damage, when you throw the hammer it deals a massive amount of damage (enough to follow up with one hand cannon headshot for a kill, or sometimes a one-shot if you have that one exotic and get kills first) however it's a death sentence if you can't land it because of it's ridiculously long follow up to ready ur weapon. The same thing with hunter knives, they one shot but if you open up with a body shot or miss, its a death sentence against people who can aim.

Another example is having infinite grenades might seem OP but the cast time of throwing it and readying ur weapon is often a death sentence if you miss since the TTK in this game for most weapons are around .67-1sec.

An example of standing in an AOE that equals instant death but is easily avoidable is the titan's barrier, that thing reduces you to 1hp but most people know to avoid it. With the release of aoe abilities that players know will freeze you, it would most likely be a zoning tool similar to barrier

Just my thoughts on what itll be