Counter target activated or triggered ability. If a permanent's ability is countered this way, activated abilities of that permanent can't be played this turn. (Mana abilities can't be targeted.)
"He slimed me...I feel so funky."
—Dr. Peter Venkman
NM-Mint - $11.30
Lightly Played - $10.20
Moderately Played - $9.10
Heavily Played - $7.90
Damaged - $5.70
NM-Mint Non English - $11.30
Lightly Played Non English - $10.20
Moderately Played Non English - $9.10
Heavily Played Non English - $7.90
Damaged Non English - $5.70