Currently, Dark Harvest is among the most contentious runes among players. This extends to almost every ELO and generally is seen as a problem, as it ends up stifling other summoner spells. Rather than a generic rant post, I'd rather go through the quick history of Dark Harvest and propose possible solutions to it.
#The Beginning: Bad Season for Crops
At the start, Dark Harvest was a member of the Domination tree with a rather simple get-up: Large things/champions give you a stack of the harvest. Your next auto in about 20 seconds will deal bonus damage and add a stack ot it. At 150 stacks, you can hold it for far longer. This made a neat little trifecta of runes for Domination:
* Take electrocute if you're a combo mage/assassin interested in quick, rapid combos.
* Take predator if you have to run into combat and/or run someone down.
* Take Dark Harvest if you're the farming type who wants to do dank damage late game.
But what was the problem with DH? It never saw much play until electrocute got demolished?
Simply put, DH was too slow to stack, didn't provide enough benefit and didn't have an easy method of activation. You had to auto to proc dark harvest and in most cases, weaving an auto mid-combo didn't provide enough of a benefit. In addition, some kits just didn't support an extra AA. This made the spell quite niche, mostly on AD-based champs who could afford a "one hit mega combo" like Wukong, Miss Fortune or other lethality characters. The slow stacks meant you wouldn't be hitting hard and even getting stacks might mean you miss out. It was far too feast or famine, with an emphasis on famine.
Seeing this, Riot took it in the direction we see today.
#Today: Farms of Doom
Dark Harvest was changed in a variety of ways, most of which we know. It's an execute summoner spell that deals a small amount of bonus damage that ramps up with each harvest. Perhaps the biggest change was that now, Dark Harvest procs on _everything_. A dot. An AoE. Single targets. You name it, it probably procs on it.
This, however, has lead to a major problem. It harkens back to the days of Thunderlord's Decree, where the keystone was generically good one everyone. Namely in that it can be procced on everything. With no internal cooldown, multiple times. Perhaps the most egregious example with current Dark Harvest is duo lanes. As there's no internal cooldown on Harvest per person being hit, you can chain 2+ harvests on the same character. This means you'll be getting people chunked down quite a bit from about 40+ bonus damage.
Dark Harvest, as it stands, is too universally good for being too easy to proc. We see this in the rise of dark harvest comps and people picking champions who can easily activate it.
#Improving Dark Harvest: Use a sickle, not a wheat thresher.
Most people want to completely revert DH from the way boards approaches it, but I don't think that's particularly healthy. Dark Harvest was only taken when electrocute was nerfed due to damage constraints, so instead I believe the spell should get generic nerfs around to lessen how useful it is, rather than making it too universally good. Below are a few ways to hit the rune in ways that don't just "nerf damage".
* A.) **Nerf the Stacking:** Right now, Dark Harvest is too easy to stack. 50% is quite easy to hit in lane and from there, it allows Dark Harvest to begin going upwards as early as 1-2 minutes in lane phase provided you take a bad trade. One way to make this more difficult is to lower the activation limit. Have Dark Harvest proc on 20% health, which scales up to 30%, then 40%, and finally 50%. It makes it harder to stack while rewarding all-in champions.
* B.) **Nerf the Proccing:** As previously stated, the proccing works on....everything. Instead, have Dark harvest proc _only_ on single-target spells or auto-attacks. This way, Dark Harvest is still good for quite a few champions while making it works on characters like Brand or Karthus who mostly proc it by DoTs or heavy AoE abuse.
* C.) **Nerf the Multi-proc:** Nothing feels worse than getting triple-chunked by three dark harvest users. In much the same way pyke has a (faux) ultimate that lowers all the HP of everyone on the map by 25% or so, so too does Dark Harvest lower people's HP metaphorically. Instead, I'd give the spell an internal CD _on the person you proc_, making it so that you can't chain-proc Dark Harvest. This in turn makes it worse on multiple champions while also lowering stacks that can be earned on a teamwide basis.
* D.) **Push Dark Harvest towards Stacking:** Right now, Dark Harvest is good at all stages of the game. The base damage is ok, the scaling makes it better and it has an OK ratio. Instead, maybe Riot can lower the base damage to quite a degree (2-36 damage) but instead make the souls increase the ability's scaling allowing it to be **THE** late game assassin option.
Dark Harvest is probably a better design than it was before as it's more useable by more players and champions. However, the rune has clear problems about being TOO useable. Personally, I think Riot should focus on making the rune less effective and give it a cleaner niche in the game's repertoire of runes. Once it gets a better niche, it can be made into a better experience for all.