"At the beginning of your end step, proliferate." It hard to imagine a line of text that embodies "long-term growth" better than that
Its hard to figure out how these cards will play out without knowing things like the speed of the format or the relative power levels of the colors and archetypes
Aside from the potential name of the card - Liliana, the Last Hope - there is no further information available on the card's abilities, nor has Wizards of the Coast commented on the existence of the card
Its a shame that the exhaust ability only works once, but its well worth it to draw at least five cards and increase the Trailblazers energy production, especially if you can often activate it the turn you resolve this creature for immediate impact
At this price, its hard to go wrong
If Banishing Light leaves the battlefield before its triggered ability resolves, the target permanent won't be exiled