true, you could use it as an alternative completely and view it as such, but it could also be used in conjunction with. reverse time would slow down the opponent and drain their quanta (assuming they play the high cost creature again the next turn). if it were then followed up by a stop, it would then function as damage control for that large creature. but yeah, ill think up a time shield when slow|stop makes it past level 1.
if i could change it back to plain n with a cap of 8|12, i would prefer to do that, but i dont think i could fit it in the text block.
edit- unless it were to be "Shield: physical damage reduced by N. N is the number of creatures that attacked last turn, up to 8" and "Shield: physical damage reduced by N. N is the number of creatures that attacked last turn, up to 12" those fit, barely.