The first priority is straightforward: They need to figure out how much cap space they are working with here. Are any and/or all of Morgan Rielly, Cody Ceci, and Ilya Mikheyev expected back prior to the playoffs? If not, the Leafs can take advantage of the space to bring in a player of consequence.
Just to clear something up: If Mikheyev OR Rielly OR Ceci are out until the playoffs, their cap hit(s) can be replaced before the trade deadline. The NHL closely scrutinizes this I'm sure, but if there's a legitimate injury timeline there's language in the CBA to allow it.