Good and bad astrals:Red astrals are best, yellow/orange is 2nd best, purple is 3rd, blue is 4th, and green has the lowest stats. However, a red astral that you don't need remains worse than a green one that you do need.
See here for more info as well:
http://www.bbgsite.com/content/2013-07-23/20130723040045382.shtmlhttp://wartune.wikia.com/wiki/Astralhttp://forums.gamefuse.com/showthread.php?2076-The-Definitive-Astral-GuideEnergine is a unique astral that feeds a given astral 500 points.
Good for Archers:Force (PATK)
Sniper's Edge (Crit) and Determination (+ crit damage)--always use these together
Fortitude (PDEF) and Willpower (MDEF), depending on who you are fighting
Brilliance (Hit Points)
Goddess Blessing (reduces damage by a %%)
Enshieldment and Illusion: A chance to reduce incoming damage. Enshieldment is better, but both can be used at the same time. These are generally lower in usefulness than the ones listed above.
Good for Knights:Force (PATK)
Fortitude (PDEF) and Willpower (MDEF), depending on who you are fighting
Brilliance (Hit Points)
Enshieldment: You should have a skill that heals you for a bit when you block. This makes block a high-priority stat for knights.
Will Destroyer: If you level this one enough, every hit will hit harder than a normal crit. May not be ideal for world boss, since world boss is guaranteed to be crit on some hits (replace with Determination then).Goddess Blessing (reduces damage by a %%)
Good for Mages:Mysticality (MATK)
Fortitude (PDEF) and Willpower (MDEF), depending on who you are fighting
Will Destroyer: If you level this one enough, every hit will hit harder than a normal crit. May not be ideal for world boss, since world boss is guaranteed to be crit on some hits (replace with Determination then).Brilliance (Hit Points)
Controversially: Enshieldment (Block)--not sure if it's great, but many mages use it.
Charm is also better for mages than for anyone else.
Situationally useful for anyone:Guardian Angel (reduces chance of incoming crit): Good if facing an opponent who relies on critical hits (archers, crit knights).
Charm: (only in solo content or battleground fighting, and have no other good astrals)
Deflection: Probably useful in some situations, but it's a gamble.
Ruthlessness (Floating Damage): A gamble for short fights. Statistically the same as an empty slot for very long fights.
Regeneration (chance to heal you for a %): Only a 10% chance, but can heal for a large amount, up to 50% of damage dealt.
Rarely or never useful:Aegis (reduces incoming damage by a flat value): Useful at low levels. Very weak at level 40 and above, but can have value in tandem with stronger defenses. In short, if the incoming damage is high, Goddess Blessing is better. If it is low (such as, near 2000), then Aegis is better.
Blessed Health: 10% chance of giving you a small heal. If small amounts of hit points matter to you, go ahead. For most of us it doesn't matter.