Updated in accordance with MKxJumps May 2019 E3 Tier list. Note only the End game columns for PvP and PvE have been updated. However, Kamath and Oberon haven't been updated in complete accordance because CC is still good in Tower of Oblivion, where six enemies can be affected.
0 - God
Highest tier in the game. Use these heroes if possible. They're your long-term goal.
1 - Excellent
Excellent tier. Very viable heroes that will follow you for a very long time.
Using one of these will make it Tier 1.5, but using more than one will make it Tier 0.
1.5 - Exceptionally High
A tier whose heroes are either less potent or a little easier to counter than Tier 1. Still excellent choices for any team.
2 - Very High
Very high tier. Heroes in this tier can be really rewarding.
3 - High
Pretty good tier. All of these heroes are viable picks.
4 - Mid
Average tier; neither good nor bad. Pick these heroes if you have no better option.
5 - Low
Very low tier. If you have to use these heroes, replace them as soon as possible.
6 - Food
Everything is in the name. Only use them as fodder for other heroes.