When you hover over the character list on the main page, some symbols should show up to show you what tags each crusader has. They're characteristics of each crusader. Some of the crusaders share tags. Getting debuffed for each unique tag means that each different symbol, or tag, reduces your dps by X amount. For example, if you have 2 crusaders with the sword (dps), you will get debuffed for having the sword in your active formation, but only once because repeated tags don't count. So 5 hearts (support) + 10 swords (dps) + 3 pumpkins (events) would only debuff you for 3 unique tags.