Always look for opportunities to use your w. If your teammate is being chased nearby, plop it down and slow the enemy, and they get away. If and ally is chasing someone, plop it down, the enemy gets slowed, can't escape and you get a gold medal! (and 150 gold):D Also good to use late game if a minion wave is pushed or being pushed. Try to use it on drag or rift/baron if you have vision, and to see if the enemies are there.