Sub-Mariner gets +1/+1 for each exhausted
Marvel Defenders character you control.
Being a king has its advantages
Chances are this guy's not going to get
much bigger than 14/13 and to get that,
your 4 and 5 drops are going to have to
be exhausted. No big deal; just have
your other guys use their back-up
abilities or have them attack before
Sub-Mariner.
Having an on-average 14/13 6-drop is
huge, but I'm a bigger fan of Silver
Surfer at 6-drop. Whereas Sub-Mariner
can do a little more breakthrough and
quite often without stunning back, the
Surfer can do irrepairable damage to
your opponent's field by getting rid of
a character (most likely their 6-drop)
for good. If you do that, your opponent
should be ripe for the picking.
In
short, Sub-Mariner should most likely
never be your first choice for
constructed.