Just so there's no confusion: While Lalisa's dream (which I color coded keywords and effects stemming from it pinkish purple) was all in her head, Seren's illusion manipulation is quite real. It pulls from people's dreams, and cloaks them. Normally this would only effect one particular target or the dreamer, but right now Seren's sort of in die or try mode (with the swarm of spirit leeches suckling them dry to their exhustion to the psychological strain of Lalisa's dream on them to all the way back to the fact they're still a little traumatized by their first experience with spirits from outside), so I think it's reasonable to assume a survival mode power spike is in order(plus as stated in their CS, Seren's powers grow while they sleep/are unconscious anyway), thus allowing all of you to see the illusion of what they pulled from Lalisa's dream. It can be described as OliveYou put it:

[quote=@OliveYou]
left hand begins to crack, splitting open from the palm to reveal not blood or bone, but thousands of flowers. They spill onto the floor, taking root, and vines growing outward from her fingertips ... Her fingers twitch, and green grass grows up to touch them
[/quote]

It's still an illusion, so however believable it is to your Character's is up to you to decide based off of their own mental constitutions.