At first, I thought somebody would complain about the Plarium support again. 😁

The descriptions given to the champs in game, like support, attack and so on, are not really relevant. It's about what champions really do with their skill skit. For example decrease def on all enemies. Dhukk the Pierced is called defense champ, Warmaiden, Armina and Tyhlessia are called attack champs, Stag Knight is called a support champ. The description may differ, but they all have the same role in the game.

How do you know wich gear is good? In the end, it's, well, ... thinking.

Champ that can revive others: high survivability stats (defense, hp and res). A reviver that dies first in his team doesn't help, it has to be the last man standing.

Debuffs on your enemies: speed and accuracy. What neither debuffers nore revivers need are crit rate, crit damage and attack.

Champs that can deal heavy damage: their damage increasing stat, crit rate, crit damage.

That is, of course, only a rule of thumb, not a rule. Dhukk the Pierced is a debuffer, but he needs crit rate. Because his own skill says it will place the debuff only, if he lands a critical hit. Read the skills of your champs and you will get an idea wich items are good.

There's no hard and fast rule because it will always depend on your team's composition. However, it's common to have buffer/debuffer + nuker + healer/reviver + 1. The +1 could be someone who does a bit of attack/heal/buffs, to add to the team dynamic. But it's always about the overall team more than anything.

 The post above all have really good advice. 

If you look at a champion under the "Skills" tab, you will see that each of their skills have a note - "Damaged based on: XXX". So if it say Defense, they get all of their damage from their defense stat. Attack does ZERO for a defense champion's damage. If it says HP, then their damage is based on their total HP, again, Attack will do ZERO for their damage.

For the short version... if you're early game... SPEED, SPEED, & more SPEED. 

In the begining, if it has a speed substat it's almost always worth wearing.

The faster your champions are the more times they attack, the faster they cycle through their skills, the more total damage they can do. If they are in Lifesteal gear, the more they will heal themselves. 

Farm Campaign stage 6 for good speed gear early game & stage 8 for Lifesteal gear. 

My rule for leveling gear is: 

1*, 2*, & 3* - don't waste silver on leveling it at all. 

4* - don't level it past lvl 8 (unless it's speed boots, then I will go to 12). 

You can start taking 5* & 6* gear to 16 if you have the silver.