He couldn't have killed her with a single thought because of her extensive mental shields. Well, he probably could have, but it would have taken some time. When Rhys tells Feyre what happened when Amarantha took over, he says that he was too busy trying to break through her mental shields to notice the spelled (or poisoned, not sure which) drink. Which must mean that even for him, her shields were very strong, and would have taken more time and effort than they had at the time when Feyre broke the curse.
Now onto why it was Tamlin that killed her. I think it was because Rhys tried before the curse was actually broken (so he wasn't at full strength), and failed. Then, once the curse was broken, he wasn't strong enough to be able to do it himself.
Now onto why he was planning for Tamlin to do it. Now this is probably the least thought out of my three paragraphs, but I think it was because he wanted to maintain his image as a "bad guy". If he was the one to kill Amarantha, people would probably wonder why he suddenly had a change of heart. And at this time he was still trying to keep Velaris a secret. So, he planned ahead and made sure someone else, who everyone expected (a.k.a Tamlin), killed her. Then he made Tamlin angry to give him the best possible chance of killing her, even if things went a little south.
Hi! And welcome!
She didn't change her entire anatomy to Illyrian anatomy. Just the part where a child would be created/come out so, in the future, she could have children with Cassian without risking baby wings tearing her apart.
When she did that, though, there was something (believed to be the Mother) that prevented them from fully leaving. She still has some of the power left.
WARNING: SPOILERS AHEAD IF YOU HAVEN'T READ ACOWAR.
I don't believe she got siphons, unless I missed something in one of the books. I do remember, though, that Rhys doesn't have and can't even use siphons because his power isn't Illyrian. His High Fae abilities get in the way of the siphons doing any good. And if I remember right, it actually made things more difficult for him. So, I would assume that because Nesta doesn't have even a little bit of Illyrian blood in her, the siphons wouldn't work for her, either.
As for the fanart, I don't know why she has siphons in some of them. Maybe it is to show her Illyrian spirit (we see in ACOSF that they keep comparing her to Illyrians), or maybe it is to show her relationship with Cassian (probably less likely than the previous option).
(On a side note, it could be possible that they would work, because in ACOMAF it said that the siphons were to control the brute power of the Illyrians. If I remember correctly, it said that power was death or death related. After Nesta gets her power, it was guessed, then confirmed, that her power is death. So the similarities of the powers may have allowed her to use the siphons. But this is just speculation and could be wrong just because Nesta could control the power without the help of siphons. Or at least keep it at bay. Controlling it may be a bit of a stretch. Which could actually prove that siphons might be useful for her.)
The last part is a bit of a stream on consciousness, and I wrote things as I thought of them, so it isn't all that well thought out. At the end I offered information that could prove or disprove my theory so that you would have all the information (at least the stuff I remember). If anyone has thoughts on that last part, I'd love to hear them!
Hi and Welcome!
14. Leave your Solstice gifts unattended
#3 is actually the home screen on my phone
10. Tell an Illyrian that they have an impressive wingspan. (ego would go through the roof)
(i started a Madja page and it's not very good, so if anyone wants to edit it, please do so.)
(@Nesta&Cassian4ever, have you played Madja before?)
(how are you?)
6. Make a bargain
(hi! I'm here, but I can't RP today. I'll be on tomorrow, though)
(I have to go too. See you guys tomorrow!)
Medea looks at Felicity. "Calm down? CALM DOWN? I don't remember seeing your mate being kidnapped by her psychotic brother."