One of the issues of St/GS is how hard it is to keep the enemy inside your triangles, as Bunda stated, you don’t really have the CC to keep enemies positioned so MW lands properly. This isn’t all that important in PvP where the most important thing is pressuring enemies on points (and St/GS excels at this, like Benjamin said), but when solo roaming in WvW you want to actually down your enemies so your server get points for stomps, and a skilled (or even average) enemy will know that staying at a distance from your clones is a good way to keep you from dealing too much damage. Therefore, you need to keep them in clone distance.
If you insist on running St/GS in WvW (I did for a while, but I got tired of people just running away after killing my iBerserker, now i run Sw/x + either GS or Staff depending on mood), you need to be quick. Having the element of surprise with help out, and landing a quick iBerserker to cripple them, then Mirror Blade (traited with Illusionary Elastacity) and either blink into dodge or just a dodge depending on distance for a full 3 clone + yourself MW will set your enemies back a good deal, and if you follow it up with a weapon switch into Chaos Storm and you get them frozen/dazed, you’ll hopefully do enough damage/CC to finish them off before they can run.
Utilities-wise, I would swap the condition mantra for Null Field (I love Null Field
), as you’ll be able to remove conditions as long as you stand in it (not just a single removal), in addition to removing the buffs (stability for example) of pesky warriors/thieves that jump on you. It’s also a combo field, so it’ll grant chaos armor if you Phase Retreat out of it. Lastly, it’s easier for teammates to run into your Null Field for condi cleanse than to ask for a mantra pop, unless you’re on voice chat.
As for portal, unless you’re running team PvP or an organized roaming team/staying behind in an enemy tower/keep/castle in WvW, I think there are better options, as you won’t usually have the coordination with strangers to make full use of it. In that case, Decoy can be a great substitute as it’ll grant you a setup for the combo described above (you can see Helseth using Mass Invis/Decoy to throw his enemies off guard and make sure he has an advantage in some of his videos), and remember that it also creates a clone, so if you’re desperate for just a tad bit more burst it can be used for clone generation (though it’s not advised). If running with a zerg you could think about swapping portal for Veil as it’ll give a lot of utility for the zerg.
Those are my two cents, good luck and keep at it!
EDIT: Forgot about the AoE part. What you could do is try to bait out the AoE skills by creating just one or two clones at a time, so that the enemy will “waste” the skills and so that you have enough clone generation to land a full MW once their skills are on cooldown. The other way to deal with them is to set up and perform your MW fast enough that the enemy doesn’t have time to react (again having Decoy/Mass Invis/Blink can help a lot in doing this as it can give you the element of surprise).
(edited by Storm.4079)