How to let Morde duo without an XP passive

Change his W to be the following:

Harvester of Sorrow Passive: Removed Active - First Cast: Mordekaiser surrounds himself with an aura causing damage to enemies in the radius. If an ally is targeted, or if an ally comes into range after the ability was self-cast, they gain a buff: Disciple of Sorrow

Disciple of Sorrow: All spell damage dealt by this champion works with Mordekaiser's Iron Man passive, shielding Mordekaiser for 12.5% of the damage dealt, doubled to 25% against enemy champions. Additionally, Mordekaiser and this unit gain 75 bonus movement speed when moving towards one another. Finally, if this unit gets close enough to Mordekaiser to connect its radius, equal to the radius of Mordekaiser's damage aura, it gains the same damage aura. Units in overlapping areas of damage only take damage from Mordekaiser's aura (effectively this just increases the total area of Mordekaiser's damage).

Active - Second Cast or Buff Expiration: Mordekaiser constricts both Disciple of Sorrow and Harvester of Sorrow, dealing magic damage to every enemy inside either area of effect. Units in overlapping areas take only one instance of damage. For the first two enemies damaged this way, prioritizing champions, Mordekaiser and his ally are healed. Enemy minions provide only 25% healing.

So basically, the xp passive is removed. Instead, morde can steal the damage from his ally to help keep his shield up in a duo lane, encouraging side-by-side fighting. Note that allies can fill his shield or be healed even if they are not in range to power the "damage" portion of the aura. This is to allow morde to be front-line when with a long-range support. It also allows a tanky engage ally, such as leona, to give mordekaiser an early heal before he is in-range if he wants to extinguish the aura early (aka poke healing). This would also open up for morde to be a support champ in some cases, since it is no longer critical for him to be last-hitting everything. Finally, since Morde always has the damage aura, he can function in a solo lane again.