Ok so there are a couple things that are both good and bad about all of the runes, except the equivilant exchange which is fine as is.
Lethal Blade- There are a lot of thing about this that are way too strong. Concept wise it sounds great for early game power farmers and assassins. problem is is that the amount of damage it gives is too much. If those full stats are given at level 1, than unless the enemy constantly wards your jungle you can be walking around with more than most completed items worth of damage. It does say that it "racks up" so maybe it would be fine if you had to stay unseen for an entire 3min or something to get it and that it didn't start "racking up" until the first camps spawned or the max amount it can "rack up" to scales by lvl. another problem is that value wise it gives too much more AD than AP- for these kind of things you want the AD to be about 2/3 of the amount of AP aquired, but the pen is fine.
DFT-like the idea but there are issues. say you hit the person with two spells and an auto early game. first spell deals 70damage and the second does 80 while the last auto only does 30. what is the dot based on. is it 60% of the last thing that hit. or is it like a bunch of stacking dots. Also 60% is way to much for something with no cooldown. Either the damage needs to go down, there needs to be a cooldown, or it needs to work like grasp and conqueror where it would proc after being in combat for 4s and than to reproc it you would have to stay in combat for another 4s.
runic heart- how much damage you dealt? Like to the target that died, or damage you did in that 3s. because if its just damage you did in general within the past couple of seconds (like maybe 4s) it would be better on anybody who dealt a lot of aoe damage. most things for fighters do single target burst/ sustained damage and tanks do a mix of single and aoe damage but it tends to be verry little. The champs who would get the most out of this are marksmen who use
or mages who have some aoe so that they can get a decent heal every time an enemy dies in a team fight as long as they contribute to the damage.