(also if you had a dark lady with multiple runed cleavers and a harkons does harkons splash through dark ladies leap? and does it stack with the runed cleavers as well)
While I'm not sure about RA splashing harkons, though I'd imagine the damage is reconverted to physical and that instead is splashed (Though you can test this yourself in practice mode, this isn't exactly hard to set up...)
TDL however - everyone in the leap will be affected by harkons, as each target is hit individually within the wave.
Never stack runed cleavers 1st.
Probably would do magic damage since it also gets lifesteal from a whispering helm.
It is an attack modifier, as harkons will only apply on attack, so no, if you attack someone with harkons and runed cleaver, only the one you attack will get the harkons effect.
"death smiles at us all, all a man can do is smile back."
I thought the OP meant is the magic damage splashed rather than the effect. Latter is a bit obvious, former I wasn't so sure. ^^
I just tested in practice mode, the splash damage from Runed Axe isn't magic
If DL charges through 2 people with multiple runeds and harkons, they will both take magic damage and get the debuff because DL's charge deals one attack to everyone she passes through. So if you charge through 3 people with 2 axes and a harkon's, each will take auto attack damage (in magic) + 160% (80% splash from 2 axes twice) auto attack damage in physical.
There's nothing wrong with stacking cleavers. If you can guarantee grouped up enemies then I'd do it.
Riftwalker/Flux for set up
Legionnaire/Chronos/Pharaoh for keeping them there.
In fact Pharaoh has the synergy with mummy wall and being melee built in, so he'd do well from stacked cleavers. Plus he's got pretty good STR gain so you'd don't miss out by building pure damage/regen with multiple cleavers. Other heroes should be wary about their resilience, especially agi-melee.
But this is about Harkons! Shame it doesn't splash with runed, it really should. Sometimes I think Harkons is implemented poorly. It'd be nice to see it apply to single target skills too. Like Deadwoods ult, lawl, boom 950 magic damage, -5 magic armour. Hmm I can dream.
However, the sole idea of making spells applying the -magic armor debuff seems nice. But it is almost like spellshards then.