That Feeling When Knee Surgery

When That Feeling When Knee Surgery enters the battlefield, target opponent loses half {x} life, rounded down.
If {x} is more than
•{2} this creature has haste
•{4}this creature has trample
•{6}this creature has flying, put a -1 -1 counter on it
{bull}{8}this creature gains "{t}: Search your library for any card with the word 'Knee' on the card, printed."
When this creature dies, gain 3 life.