Very simply, a tank's job is to protect the other members of his team. This involves absorbing as much damage as possible, using CC to disrupt the enemy team, and pressuring the enemy team to focus on you instead of your carry. Tanks are also usually responsible for initiating team fights.
Why Should I Play a Tank?
A balanced team composition will always include at least one tank. This may be a "hard" tank (e.g. Rammus) or a character who fulfills two roles at once, such as a jungler-tank or support-tank. Having two or more "off-tank" characters is also common. Regardless of what kind of team strategy you're picking around, your squishy damage-dealers need protection, and that means tanks.
Which Stats Are Important for Tanks?
Health Points (HP), Armor, Magic Resist (MR), Health Regen, and sometimes Move Speed (MS).
High Armor and Magic Resist stats are the hallmark of a good tank. You need to understand the underlying math to make good use of them.
Armor reduces incoming physical damage according to the formula:
% Received = 100/(100 + Armor)
Therefore, at 50 Armor, incoming physical damage is reduced to 100/150 = 66%; at 100 Armor, 50%; at 200 Armor, 33%. As you can see, the more Armor you have, the more it takes to improve your defenses. In other words, we say that Armor has diminishing returns. The formula is exactly the same for magic damage and MR.
Another, more intuitive way to understand resistances is to flip the formula around and state it in terms of HP. A little mathcraft gives us:
Effective Health = Health Points * (1 + Armor/100)
Said another way, each point of Armor increases your EHP by 1%. So for example, a Shen armed with 3000 HP and 75 Armor effectively has 75% more health vs. physical, i.e. 5250 EHP. Again, the calculation is identical for Magic Resist.
The bottom line is that at a certain point, it's not as effective to just stack Armor or MR compared to building Health. Think of Effective Health as a rectangle whose sides have length equal to your HP and Armor - the best way to maximize the area to increase both sides. Also never forget that building HP increases your resistance to both physical AND magic damage.
To be an effective tank, you must carefully gauge what kind of damage your opponents are armed with. This is a skill you will develop with time as you play with more and more different characters. The best way to learn is to pay attention to the death reports each time you die.
Physical vs. Magic - Every champion's auto-attack deals physical damage. Most champion abilities deal magic damage. You can usually count each character as one type or the other, but be on the lookout for hybridized abilities, armor/MR shreds, and abilities that deal damage as a % of your total health. Also know (and fear) characters that can deal true damage - you can't mitigate it.
Burst vs. Sustained - Most abilities deal a large chunk of damage immediately (burst). Auto-attacks, spammed abilities, and damage-over-time (DoT) effects. Notice that Health Regen will protect you somewhat vs. sustained damage, but is useless against burst.
Single-target vs. Area-of-Effect (AoE) - As a tank, you want to be aware of the targeting of each enemy's skills, their range, and how you might be able to intercept them. Look for opportunities to "catch" incoming skill shots, but be aware that some will penetrate units (i.e. Caitlyn's Piltover Peacemaker).
Understanding Crowd Control
Crowd control (CC) refers to any effect that disables your opponents. We can separate them into "soft" and "hard" (channel-interrupting) types.
Soft - slows, roots, snares, and blinds
Hard - taunts, fears/charms, silences, stuns, knockups, displacements, and suppressions
- Make sure your team has a good amount of CC skills before you lock in - they're critical for shutting down important targets.
- Some CC is conditional, i.e. dependent on enemy position or surrounding terrain. Don't count on them to always be available.
- Good positioning and Tenacity (Mercury's Treads) are your most important tools against CC, but remember that knockups are unaffected by Tenacity. Consider taking Cleanse or a buying a Quicksilver Sash if you see a lot of hard CC on the enemy team.
Most of the time, your team's tank acts as the leader. As the front line of your formation, they are chiefly responsible for initiating good team fights. This is a very difficult skill that depends on many factors, as well as gut instinct. Here are a few tips:
- Tank first. Squishies in back. Stay together.
- Look for an opening in the enemy formation and exploit it. Choose your moment and commit to the fight. If your initiation skill places you in the middle of them (Amumu), be sure the rest of your team is ready.
- Be wary of counter-initiating skills. A Sona or Janna ult can completely turn the tables on you.
- If you're running a poke comp, DON'T initiate. Your goal is to shield your team from the enemy while they poke.
The best way to remain an effective tank is to stay ahead of the enemy, so buy defensive items before you need them. When you get to the loading screen after champ select, look at each enemy one by one. Gauge the balance of magic vs. physical damage, count the amount of CC skills, and remind yourself when each champion is strongest. If you plan ahead, you won't fall behind.
Example: the enemy team is Vayne, Rammus, Sona, Leblanc, and Gangplank. Counting the CC, I see-see that Vayne has a conditional stun, Rammus has a slow and a taunt, Sona has an AoE stun, Leblanc has a silence, and Gangplank has mild single-target and AoE slows. Right away, I know I'm going to need Mercury's Treads here. Beyond that, the first problem will be Leblanc's incredibly high magic damage - a Negatron Cloak will likely be my first important buy. As we get into late game, Vayne will become their main source of damage, so I'll want a Frozen Heart, Randuin's Omen, and/or Thornmail. If Gangplank starts getting farmed, I'll need them sooner rather than later. Rammus and Sona have negligible damage but godly initiating and counter-initiating skills, so I'll have to be on my toes.
So that's it for now. Later this week I'll continue by going through each defensive item and how it can help you maximize your tanking potential. 'Til then!