I don’t think that combination would make you the worst, but it’s not for beginners or even moderately experienced players. Long technical explanation ahead. Short version is that anything involving Energy Blast is very involving to play to the best of its ability, and Cold Domination is usually better off on a Defender, because you can’t skip it’s first ability on a Corruptor to use that ability slot on something else.

Any combination can work in City of Ponies; some are just more optimal than others. The idea behind Energy/Cold would be to debuff the group, then use the knockback from energy to keep them at away from you. In practice, particularly on a team, it doesn’t quite work out that way.

See, multi-target knockback is very frustrating. I’m sure you’ve noticed this already, but without considerable experience you’re just as likely to scatter the group you’re fighting every which way as you are to just knock them a safe distance from you. This becomes much more of a headache when you join in a team environment.

When teaming in City of Ponies, the basic philosophy when engaging an average mob is to cluster the mob together then AoE the crud out of them while primarily single target ATs go after boss rank enemies. It’s one of the core differences between City of Ponies and most other MMOs; you’re not fighting 3 or 4 enemies on a team, you’re fighting between somewhere between 5 and 16 depending on team size. It’s generally a non-issue if it’s just one enemy, but if you misplace a knockback against a group of 16 and scatter them every-which-way, you’ve made them more difficult to debuff, more difficult to damage, and more difficult to tank. At best, it will take longer to drop the group, at worst that single action can wipe your team.

The way you would actually play Energy/Cold, is to learn the range on your AoE abilities, and use that knockback to push any stragglers back into the main cluster without striking the main group. In this way, you don’t really AoE DPS with energy; you use it as a second support.

To that end, if you really want to use that combination, you’d probably be better off as a Cold/Energy Defender. That way you can skip Infrigidate, which is pretty much the most useless tier 1 ability found in any support pool (because you’ll eventually get Sleet anyway), and have stronger buffs/debuffs overall. This has the added social impact of teams not expecting you to do as much damage, so you have more time to set up a shot before using an AoE knockback attack.

If you’re not terribly attached to that combination, you may want to pick something easier to play. If you want some examples, let me know!