Sirene Primer+Typical Tactical Opening

Generally, Sirene will start each battle with 2 tension and an opening to generate more:

Swift: Shadow Shield for 9d4+9 temp HP.
Move: Shove for minimal damage (5), but +1 tension.
Dual Attack: Either the whips, two unarmed attacks, or a bite + unarmed attack.  +1 tension if she connects.

If she's in her constrictor form, she may followup her bite attack with a free grapple attempt, and a constrict.

If she's attacked, she'll generally use her immediate action to get 30% concealment (Umbral Mantle).  This will last the length of most fights.  If she's still injured, she gains +1 tension.

Later in the battle, she'll use Fiery Offensive (dumping as many as 8 tension into it), to get a significant bonus to her unarmed attacks and damage.

For everything else, like her basic attacks, you should be able to use the macros in Fantasy Grounds.


Spell Primer:

Whenever Sirene casts a spell, there's a 10% chance that she'll trigger a wild magic effect. So if the d100 is 10 or less, roll again and use the result of that to look up the wild magic table for whatever sphere she's using. For example, if she's casting a cure spell of the life sphere, and she rolls a 7 on the first d100, then she'd roll again for say a 42 and reference the wild magic table at the bottom of the life sphere's page on the wiki.

Now for the confusing part. Flexing talents. Basically, the whole idea of Sirene's build is that she can cast spells that she doesn't normally know by temporarily gaining knowledge of certain spheres and talents. She can do this in a number of ways. The all-day access method is to shape one of the sphereshaper's veils, which grant access to a sphere. Most days she'll have Beastshaper's Cord (http://spheresofpower.wikidot.com/sphereshaper-veils#toc4), for example, to improve her alteration (snake shapeshifting) spells. But she can also shape another veil from either of these two lists:
http://spheresofpower.wikidot.com/sphereshaper-veils
https://libraryofmetzofitz.fandom.com/wiki/Sphereshaper_Veil_List
And when she does, she can select an additional bonus talent from that sphere. So for example, she could shape Shaded Spirit (https://libraryofmetzofitz.fandom.com/wiki/Shaded_Spirit) to gain access to the dark sphere and then take a talent like Shadowed Mien. You can ignore the bind effect for these veils (except for hands binds), and whenever it discusses essence, you can assume she has 2 invested. These benefits last all day, so it's good to pick up a sphere/talent this way that she'll need to use continuously throughout the day.

The default, round by round method of flexing is for her to do an Inspired Surge, where she basically accepts +100 wild magic chance for access to a talent from a sphere she already knows. This is the most limited flexing ability she has, but she can use it at will, so it's a great way to shore up some abilities (like getting access to advanced Life sphere talents to remove bad wild magic results). The +100 wild magic chance means that she's guaranteed to roll on the wild magic table for whatever spell she's casting, and there's a 10% chance that she'll have to roll on the major table instead:
 
 
Finally, she has four shadow points that she can spend to give herself access to new talents or spheres. This can be used in conjunction with any of the flexes above, but she only has the four points per day and it costs a point each time she does so (though she can trade spell points for more shadow points). This gives her access to Alteration, Conjuration, Creation, Dark, Death, Destruction, Enhancement, Light, Nature, Protection or Weather sphere for 1 minute (or until she spends another shadow point).
 
Ideally, this means that she can reach four talents deep into a most spheres, but in practice she'll only be able to flex one or two talents deep into any given sphere. That's enough to pull off things like that Death sphere Control Undead talent, but not most advanced talents, for example.
 
Generally, she's a 6th level caster with DC 18 spells and 14 Spell Points. Not all spells require spell points, but when in doubt, assume they cost 1 SP. She gets a +2 CL for Illusion spells and that increases their DC to 19. She also gets +3 CL for most caster level check calculations, like for SR, dispelling, etc. Concentration is +14.