I think it's Gowlings. (The building represented would occupy the
red square.)
The high-rise in the background resembles the
east face of One James South, but (given the "MacNab Square" moniker) is likely intended to be
the east face of 25 Main West.
Trying to untangle the layers of architectural "homage" going on in those renders. (The
Will Alsop nod is the most obvious.)