Sigma, Harnesser of Gravity

Flying, Vigilance,
{1}{u}, {t}: Create a 0/4 Barrier creature token
with defender, put an Ultimate counter on Sigma, Harnesser of Gravity.
{t}, Remove Four Ultimate counters from Sigma, Harnesser of Gravity: Tap all creatures an
opponent controls. If any of them were already tapped, destroy them instead.