Good support gem for ice trap?

I have an ice trap gem linked with cluster traps. I'm debating which support gem (if I had to choose only one) would be best to link with it. Normally I'd choose something like added cold/lightning damage, or even something that improves crit chance or damage, but I wonder if the Increased Area of Effect support gem would be better. My reasoning is that ice trap creates a series of several explosions in gradually widening rings, so I'm thinking that Increased Area of Effect would not only make the skill better at fighting groups of enemies (due to increased radius) but also against single targets, because it increases the likelihood that explosions will overlap, thereby hitting the same target multiple times. Any thoughts?

I'm running this setup (5k tooltip):


Imo Increased AoE isn't that important, ice trap has decent starting aoe, picking 1 cluster of aoe nodes is just fine, unless you would go for concentrated effect.
Penetration is a must; cluster traps helps a lot in clear speed and in damage boost; picked elemental focus instead of controlled destruction because damage isn't that great to freeze scary enemies and planning on picking elemental overload with some crit nodes. Alternatively it's possible to activate ele. over. bonus with orb of storms, but it's choice of taste.

This guy went full on crit:
https://www.youtube.com/watch?v=y4yKP5jXt1E

Dunno if it's worthwhile. With that great gear and 6L he does 14k and there is no penetration gem. with pen gem tooltip would drop to somewhere 10-11k.
It might be worthwhile going crit with assassin ascendancy, but besides that it's pretty same as any other build choice.