spamming miasma.
Whoa there. Saryn was "reworked" several times, so if you haven't used her in a while or were told how to play her by someone who didn't keep up with the times it could explain why you are bad at ESO.
How to Saryn in ESO:
First a few tips.
* Melee. Get a good heavy blade, since melee is much, much better than a gun (on Saryn) for several reasons:
1) You need to be on the move at all times. A warframe with its feet on the ground and not sliding or in a melee combo is a warframe losing health.
2) Heavy blades or polearms can nuke large groups due to their insane range with full build.
3) Your 3 works even better with melee.
* Use your 1! Your other abilities are nice, but if you only ever cast one ability make it your 1.
* Get a set (or two) of Magus Elevate. It is much easier to farm than it used to be and it is the best/fastest source of free healing in the game.
* You *need* Zenurik Energizing Dash focus node *or* a Trinity in the party. Since you can't count on a trin and/or probably don't want to be dependent on some random to know how to play trin properly, you need Zenurik.
When you go through the portal cast your 3 the instant you can. As soon as this is done, cast your 1 on a nearby enemy. If you are fast enough you will still be in the brief invulnerability period. As soon as you cast your 1, melee the enemy you cast it on. The instant you have the first batch of spores spreading, tap 5, void dash, and tap 5 again to start regenerating energy. This should give you a solid start to the zone.
From here you just need to stay alive, melee lots of enemies, and keep spreading spores (your 1). Keep your 3 up to help melee damage and make it so that you only have to hit an enemy to spread the spores rather than kill them. This will matter by zone 5 or 6 when enemy armor starts getting thicker. If you are getting shot a lot drop your 2. If you are having trouble with healing you can put the augment on your 2 and use it for healing as well, it is really good (I don't use it now, but I used to and it is very nice). Every time your Energizing Dash runs out make sure to refresh it, you will need the energy.
Last and certainly least, you can use your 4 to nuke the map. It will have all the impact of a wet fart unless you have spores on all the targets though. Where your 4 really comes into its own though is spreading spores on the larger tiles. To do this, you get the spores started then nuke the center with your 4. This spreads spores to the edges assuming the spore carriers in the center die under the effects of your 4.
If you do all this and still die, then the solution is almost certainly to keep moving! Monitor your health and make sure to keep it topped up. Move, move, move! Bullet jump, slide, roll, glide, anything but run on the ground. Melee. Melee constantly. If you see a group shooting you, melee them! Not only will you auto-block shots while you charge in, but they can't shoot you when they are dead! Since you should be in the air a *lot*, melee ground slams into groups are pretty OP.
Now, a while ago Saryn's 4 was a real nuke and could clear the map all by itself. I still sometimes see a Saryn player who thinks that still works and wonders why "Saryn is so bad nowadays".
For a good build and some info on the abilities see Brozime:
https://www.youtube.com/watch?v=suaJSJnUYqMMy build is very similar, but not quite identical to his. I have watched Brozime on stream as he just *bullied* ESO many a time, and it still took quite a while for me to figure out how to do it myself.