i disagree that a mob has to be equal to your level. its kind of arbitary. I guess its more intuitive, but it doesnt really matter much. The exp i get for fighting a monster 10 levels higher than me solo, feels right though.
maybe 20 is a lot, but we used to fight things that were probably 17+ levels higher than us all the time, and get great exp for it. The tanks really had to be on point, and the mages had to be ready to heal fast. But when you have 3 healers, why shouldnt they? The game exp used to scale up very well for parties of 3 or more.
If we had 3 to 4 people fastest exp was to chain mobs that were about 10 levels higher, even with random SP, if they had fast spawn rates, it was basically like one long continous battle. The mage spent less time curing and more time nuking, was also able to get more SP because you can siphon from the corpse and the main target.
If we had 5-8, we would be fighting something a little tough, a tough monster type with decent hp, probably like 12-14 levels higher The damage isnt that bad, and you dont need an army.
if we had 9+ we would probably go after big game, a really tough mob, with a lot of hp/defense and powerful skills, 15-20 levels higher, you would need a true tank for this type of stuff, with high hp, and high ev/def They would definately have to play more defensively, gladiator watching his stamina and blocking/taunting reaction weaponskilling a lot, and using shield skills, or a monk playing defensively with evasion boosts, high hp, and light strike up at all times, with multiple hate getting skills. you prolly had at least 2 healers, and someone to watch for debuffs. DD really need to strike hard to make dmg, and you needed a fair number of them, because tp gain was slow, and skills miss.
But it worked out that you could get comparitive good exp in a lot of dif groups
Solo though was really really bad. leves was the only thing even close to ok solo.