Yuumi is a strange support that can assist all people in the team. Her impact though not immediately obvious is definitely there. This is because of her passive play style.

Yuumi wants to be attached to players as often as possible while exiting to gain mana through her passive.

Yuumi's Q is used for harassing the enemy laners in laning phase. Don't forget that it does apply a slow that allows you to chase anyone that tries to escape.

Yuumi's W allows you to attach yourself to allies which will apply a buff to damage to both players. Attaching yourself will make you untargetable and will allow you to control your Q.

Yuumi's E is a heal that heals whoever is attached or herself if not attached to anyone. It is important to remember that the heal does apply a temporary speed boost if chasing anyone down.

Yuumi's R channels out 7 waves that deal very little damage but will root anyone that is hit by 3 waves. The direction of the waves cannot be changed so position yourself using your W both to exit and to change ally.

For Yuumi to reach her maximum potential it is very important to be in voice comms with your ADC. This is mainly because Yuumi's abilities require co-ordination to hit, when to heal and to say when to go 'all-in'. Yuumi can be described as the bot lane coach.