Make it a kinetic gem.

It will in no way give any advantage to a pudge player.

It will just be a cool passive addition to the game.

If there is a VISIBLE enemy within VISIBLE area near pudge (larger radius than hook range), it should start automatically spinning, and keep spinning, even if enemy the goes into fog of war, pudge keeps spinning, with a 15 second cooldown it stops spinning. Pudge moves, he will keep spinning until the 15 seconds cooldown.

If a TP begins from an enemy to a tower within in VISIBLE Range Radius. Pudge starts spinning before the enemy actually TP's in. As many pudge players look for the hook of a TPing hero into a tower/building etc.

Once the enemy is in Fog of war, the 15 second cooldown begins, The enemy could have, tp'd to base, gone behind to gank, but the pudge player doesnt know that.

Spin does not activate if there are invisible units within Area.

There is No advantage to a pudge player. Just looks awesome, and is passive for fun.