Therac-25

At the start of each upkeep, deals 2 damage to
target creature and put a counter on Therac.
Give 1 rad counter to player controlling target creature. Once Therac reaches 4
counters, Sacrifice Therac. At the start of your
next End step, transform Therac-25 into
THERAC and put him on the battlefield
—
You have just delivered a dose of approximately
25,000 rads of 25 MeV electrons in
less than two seconds.