"Most people can't build decent weapons out of stone or steel. Trust the elves to do it with only mud and vines."
—Gerrard of the *Weatherlight*

Llanowar Behemoth

Tap an untapped creature you control: This creature gets +1/+1 until end of turn.

Ninth Edition

Tap an untapped creature you control: Llanowar Behemoth gets +1/+1 until end of turn.

Eighth Edition

Weatherlight

Tap a creature you control: +1/+1 until end of turn

Since the activated ability doesn't have a tap symbol in its cost, you can tap a creature (including Llanowar Behemoth itself) that hasn't been under your control since your most recent turn began to pay the cost.