Today’s LoL Basics post is a quick look at an essential stat for casters: cooldown reduction. It’s one of the best ways to increase your DPS at every stage of the game and can be very easy to max out.

Cooldown reduction, as the name suggests, reduces the amount of time between spell casts. Take Karthus, for instance. His ultimate starts at a 180 second cooldown. That’s a long time to wait, especially if your team is playing aggressively. If you’re going with a Mejai’s Soulstealer, you want to at least be picking up assists as often as you can, and an ult is great way to do that in other lanes.

A lot of items offer cooldown reduction, not to mention the runes you can buy. Frozen Heart is 25% reduction. Soul Shroud is 15%. Let’s say you have both those items on Karthus. Cooldown reduction works additively, so you’re at 40% reduction. For the 180 second ult, that means you can now cast every 108 seconds, which is really nice.

There is a caveat, though: cooldown reduction caps at 40%, meaning you can’t have any more than that. If you’ve specced into utility and offense for your masteries, you likely have 9% reduction. My own rune page puts me at 10% more, which means 4% of the CD reduction on Frozen Heart is lost. Granted, it has plenty of other benefits, but you should try to be conscious of how much of an item becomes worthless for you.

Don’t forget, you can also get the golem buff for an extra 25% CD reduction and some mana regen. Before taking the buff, though, consider whether you’re the best person to wear the buff on your team. If another player will be capable of more DPS, pass it off.

So you’ve purchased a few heroes you like and you want to get started with a rune page. But what to get? If you dig around the forums, you’ll find every possible answer and likely end up no better off than when you started. This is a basic guide for understanding magic penetration runes and their benefits.

If you like to play mage toons – Fiddlesticks, Karthus, Ryze – magic penetration can be a cheap start for your runebook. For a lot of mages, though, it’s a tough purchase to justify because of the way magic penetration works. Penetration only affects magic resistance your target currently has. It’s also the last debuff applied in a string of magic resistance debuffs. It works like this: fixed resistance is applied first, so Karthus’ wall, for instance, which gives a -35 magic resistance debuff. Then comes percentage based debuffs, like Void Staff. Then, after all that has been applied you get your magic penetration debuff.

The real kicker is that penetration can’t take your enemy’s resistance below zero. Only flat resistance can do that. If you’re in some higher tier play and you’ve got enemies stacking up MR, then penetration is a great choice. It adds a level of damage you can only get from Abyssal Staff in game. If you’re a more casual player like myself, then you might see more benefit from flat AP, mana regen, or even flat health.