How to deal with Astros...

[Amiaze]

As an AST main, I can say the hardest thing to deal with is when 2 or more people are getting damaged while I'm also being harassed.

As an AST, I agree. However, I'd like to add that any time a WAR or melee DPS comes my way, I'm in trouble. Because of the way the map is arranged, I'm often repositioning myself so that my comrades don't break line-of-sight while also trying to break the line-of-sight of other casters. But if a particularly strong DPS (or WAR) comes at me and nobody is paying attention, I'm left with no other option than to use CDs and try to run away. This often means I'm running around in circles and, eventually, into the midst of the chaos because I'm trying my best to spam AoE heals to keep myself and the party alive.

...And things just sort of go downhill from there.

As a side-note, I don't have a problem with casters. I actually often ignore them, or just move behind a pillar/wall for a moment. The only one that can sort of bug me is MCH. So I wouldn't recommend sending a caster after an AST, unless they've figured out something that I haven't seen or experienced yet.

[Renault]

As an AST, I agree. However, I'd like to add that any time a WAR or melee DPS comes my way, I'm in trouble. Because of the way the map is arranged, I'm often repositioning myself so that my comrades don't break line-of-sight while also trying to break the line-of-sight of other casters. But if a particularly strong DPS (or WAR) comes at me and nobody is paying attention, I'm left with no other option than to use CDs and try to run away. This often means I'm running around in circles and, eventually, into the midst of the chaos because I'm trying my best to spam AoE heals to keep myself and the party alive.

...And things just sort of go downhill from there.

Try running behind a wall and using <Blizzard 2> to bind them in place. Then that should stop them for awhile.

[Amiaze]

Try running behind a wall and using <Blizzard 2> to bind them in place. Then that should stop them for awhile.

Thanks! I try to do that, but since it's something I've only recently adopted, I sometimes misjudged the range of the spell. It has been working for the most part, though.

Can someone explain what makes AST so good in PVP compared to SCH or WHM?

As the poster above me said, it's our ability to heal while moving. We also have two MP-restoration abilities rather than one and, if you count Stoneskin, have three different shielding spells that can all be used at once. With the right cards and a good team, AST is the perfect healer for PvP. Keep in mind that Essential Dignity is not only our strongest healing spell, but it's also an instant-cast. You can be in the middle of sprinting and it'll still work, and Aspected Benefic I only takes a millisecond to cast for a quick regen/shield.

That being said, those skills only do so much and can only be used so often. Once a focused DPS or WAR comes your way, a small shield or quick heal won't really suffice.