Mefnanim

My first thought was pairing Water Blast with Storm Summoning; a hydrokinetic psychic Mutant. So far I haven't found anything that's not to love. Excellent synergy both in power theme and function. Now if only I could stop giggling every time I start a fight with Tidal Power -> Water Burst -> Freezing Rain -> Whirlpool.
And it's only going to get worse with Geyser.

By taking the high ground, you have a line-of-sight advantage. Essentially, any cover which is LOWER than your position looses effectiveness since you can look (and shoot) over top of it.