The creative aspects during exploratory design are in their early stages, so a lot of conceptsincluding ones that come out of decisions made in designhaven't happened yet
N52 High-Power Magnets for Seamless Security
Mishra does replace the power and toughness of the Vehicle he makes a copy of, so you Tangle Tumbler will just be a 4/4
Sure, you can keep making Cat tokens over and over again, but if you have tokens of another artifact or a different powerful creature, you can quickly make an army of massive creatures
And you draw for each one even if they died at the same time
To determine a spell's total cost, start with the mana cost (or an alternative cost if another card's effect allows you to pay one instead), add any cost increases (such as kicker), then apply any cost reductions