The following Tier List focuses on PvP only.
Reserved for a Meta breaking units(). This Tier has one or Two heroes max. In a balanced Meta there is usually no heroes in this Tier. These units are so far ahead of everyone else they need a tier of their own. They rule the Meta & other units rankings are based on how well they do against this tier of hero.
Tier reserved for Meta defining units. The top of the line Staples for the Current Meta. These are the Units that are the glue to most teams. Their Versatility allows them to be used in various teams.
These Heroes are used in most, if not all, competitive team compositions. Some Team comps are built purely for countering these units.
SS- Tier Note: For high rank (4,300+) play Heroes in the sub-tier SS- typically are your 5th member options.
Great all around Units. Right on the cusp of being SS ranked. They play an essential role in the Meta. An arena staple for the most part. Hard to counter & provide at least one unique attribute that other heroes do not.
Quality Heroes; they are the bulk of the Meta. They perform well in most (if not all ) Arena Ranks & provide good utility. Other units maybe slightly better. In some situations they might be even with SS but there overall performance holds them back from SS Tier.
Units that are falling out of Meta. While you may be able get away with using these heroes in LOW Tier Arena Ranks, most are starting to (or already have) fall out of the Meta. They may still have a Niche use or add value to certain teams. They're also usually easier to acquire than top tier units, but overall they're subpar until they receive a remake / Awakening. Until then there are other Heroes who can do a better job in there place.
Seven Knights: PVP Tier List