Marino would be a shrewd move. On paper seems like a logical fit with Rielly, but could also complement a shutdown pair (I.e. with McCabe).
Versatile piece that would supplement one of the more grizzled UFA D the Leafs are rumoured to be interested in: Roy, Tanev, Zadorov. Marino + one of those names would give you a fluid, interchangeable top 4.
Also likely comes at a cheaper cap hit than any of those names, leaving money for other adds.
Marino and Colton are two secondary pieces I’m most interested in as of right now via trade.