Robert

{t}: Put a Decay counter on a target creature. That creature has "At the beginning of your upkeep, sacrifice this creature unless you pay{2}, as long as
it has the counter on it". The Decay counter can
be removed by paying {6} during the upkeep after
the one mentioned here, that is on top of the 2
they pay to prevent sacrifice.
{g}{b}, {t}: Remove a Decay counter from target creature, if you do they take 1 damage and you
create a 1/1 Insect token or a Sludge Token.