With this situation, either A. I'm completely wrong or B. Something is very wrong with this picture.
Maybe it's my imagination, but doesn't it make sense for a tank to TAKE a lot of damage, not GIVE a lot of damage. Yet, I constantly find myself fighting tanks who are getting tickled by my abilities, while they crush me into the ground....
Soudade6 votesI'm willing to bet that if you list the Tanks you're having problems with the majority of them will actually be Fighters.
L7xLoTek4 votesWell, tank characters do need to present a credible threat to the enemy team (aggro) so that they don't just ignore them and go for the squishies, be that CC or damage. Then there's the difference of tanks that tend to have good base values and late tanks that have worse base values but better ratios (=more gear dependent).
Edit: On the other hand, it feels kinda weird when playing a tank with >3k health and 200-300 armor and the ADC is just melting you like nothing :p
TehNACHO4 votesExcuse me, but I believe you're misconceiving something.
MOBA's have 3 elements, not just 2. You are currently thinking of Offense vs Defense, which is two stats, but generally the third is just as important: Crowd Control/Utility.
For example, Fighters and Fighter type tanks like Dr. Mundo or Shyvana have very, very limited Crowd Control or Utility compared to true tanks, even though you can argue that Dr. Mundo or Shyvana can be just as tanky as a real CC tank. To make up for their lack of Utilities, Dr. Mundo and Shyvana are superb power divers, as they have Tankiness and Damage for their lack of CC/Utility.
To re-explain, there tends to be three combinations: Damage+CC/Utility: Think most ADCs. While the majority of them have no form of CC, almost all of them have some form of very favorable utility on top of the fact that they are ranged and consistent damage dealers. Tankiness+CC/Utility: These are most true tanks, or CC tanks. Amumu, Malphite, Maokai, Alistar, while they may hurt somewhat if they sit on top of a squishy too long, this is nothing compared to their durability and CC. Damage+Tankiness: These are the fighters of the game. Dr. Mundo and Shyvana have already been noted, though many many others also exist. These are the champions that are tanky enough to charge recklessly into a fight without (usually) dying instantly, while also being MASSIVE threats to squishies due to the fact that their damage is high enough to threaten most, for example, ADCs.
67chrome2 votesMaybe it's my imagination, but doesn't it make sense for a tank to TAKE a lot of damage, not GIVE a lot of damage.
There's 4 damage-carry rolls in LoL: Marksman, Mage, Assassin, and Fighter. All 4 can potentially be the biggest kill-threat on the team and win in the most damage dealt to other champions post-game field.
Marksman survive long enough to do their job through a combination of range and mobility. Mages with range and CC. Assassins with amazing mobility.
Fighters that are tanky? Durability. While marksman and mages can out-range opponents and assassins can out-maneuver them, bruisers need to be able to survive getting hit to properly do their job.
Also - the more Nasus/Volibear/Darius/Shyvana/Mundo/Udyr a tanky DPS tends to get, the less mobility, range, and CC they often have. Kit them to death is generally at least a 50/50 strategy.
Scorpionex2 votesThis could go the other way why am I as a tank allowed to be melted by the enemy carries when I'm ahead of them in gold/items? Does that seem at all fair? Because that's how its been for most of the past 2 seasons which is why most bruisers have fell out of favor in favor of Ryze/Rumble/Jayce it makes me mad that a whole class of champions falls out of favor because their favorite items are nerfed or in some other way changed to better suit other classes.
Myrddin2 votesmost tanks get melted
The Mormonator1 votes
Meep Man1 votesThe only damage tanks I know are Maokai, Zac, and Cho'Gath. (Singed?)
Wehrmacht Bunny1 votesThe only tanks that annoy me in this game are, 
Two can ignore turrets like they are minion hits, and one can instant kill you without losing much health.
