If you want lifegain, Basilisk Collar and Loxodon Warhammer are your options, while Whispersilk Cloak and Maul of the Skyclaves are there in case youre looking for evasion
Of course, this means you need a character on board that can initiate the challenge before Maid Marian gets value, but there are 11 4-cost characters that all have decent Strength values, so it isn't hard to get something down the previous turn that can take the Challenge
But there are a few other cards out there that don't have the "changeling" keyword but whose effect also creates creatures with all creature types: Mutavault, Volatile Claws, Amorphous Axe, Mistform Ultimus, and Runed Stalactite
The correct build of the deck is still in flux, but you can expect something great to come out soon
But the proliferation of more strong utility lands and the improvement of some archetypes relying on lands likely necessitates more than one Strip Mine
While this is designed for unsleeved trading cards, it can be used with sleeved or toploaded cards