With powerful AoE CC tools and a focus on movement speed, Ekko and Yuumi have great synergy during the mid to late game; let’s break it down.
Ekko is a very flexible champion and has found success in mid, top and jungle. If you're playing Ekko in a lane, you’ll want to focus on poking away at the enemy with your Q and proccing your passive with the increased basic attack range from your E. Ekko’s jungle clear is pretty good thanks to AoE damage from his Q, and he can pull off successful ganks with a W/Flash combo to lock down enemies. This combo is even easier to land if you are ganking allies who can CC the enemy before you arrive.
Though Yuumi is the most vulnerable champion in the game, she can play level 1 pretty aggressively if the enemy doesn’t have hard CC; when she starts to get low, she can jump back to the safety of her ally with her W. Given how much mana her E costs, it’s important to proc her passive but only when it’s safe and the enemy’s CC is on cooldown. Casting her Q while attached to an ally grants you full control of its direction, deals extra damage, and will slow the first enemy hit.
Ekko and Yuumi both have powerful AoE CC tools: Ekko’s W can stun multiple enemies, while Yuumi’s ultimate can root them too. Once the laning phase is over, Yuumi can attach to the Ekko and cast her ultimate to root enemies while Ekko casts his W to follow up with a stun. This is a very strong CC chain and quite easy to pull off; Ekko spends a lot of time in the front line in order to basic attack enemies or land his Q, making it easy for Yuumi to root them.
Yuumi’s E also grants movement and attack speed, helping Ekko get in range of enemies to land basic attacks and proc his passive. Meanwhile, Ekko’s ultimate and general slipperiness makes him a great ally for Yuumi to attach to, as she will stay alive for a long time. This means she is able to provide a ton of value from heals and the raw adaptive stats she grants to targets she’s attached to.
Runes and Items
Ekko’s build is pretty flexible depending on his role. In the mid lane, Electrocute is a great keystone to increase the damage of his combo, while Dark Harvest excels in the jungle as you go around the map accumulating stacks. Hextech Protobelt is a fantastic Mythic on Ekko as it makes him even more mobile and makes it easier to land his W and E. Lich Bane is another excellent item and synergises with Ekko’s AP/basic attack damage focus.
Summon Aery is Yuumi’s best keystone, as it increases her damage, heals, and allows her W to proc Moonstone Renewer. Presence Of Mind is another essential rune due to how much mana her E costs. Considering Yuumi doesn’t need to buy boots, other enchanter items like Chemtech Putrifier, Redemption and Ardent Censer/Staff of Flowing Water can be completed quicker than other enchanters.
Although Ekko and Yuumi can’t team up until after the laning phase is over, they make for a very effective duo. Both of their kits are focused on movement speed, attack speed and healing, and their AoE CC tools can be chained together to lock down multiple enemies for a long time.