In 90% of cremeation decks, Ball Lightning are better purely from a burst damage perspective. Ball Lightnings will shave a turn off a decent % of your games. RoL are only really preferable if you need the light quanta to power something in you deck.
As far as your deck. I would try removing 1-2 Ball lightning for Towers and see how it effects performance. Explosions are more versatile than momentums, but since they use
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could potentially slow down the deck. its probably preference on which you like better