I ran this Lair Assault twice. I might get to run it again, but the group I run for played Guardmore Abbey this week, instead.
As with Talon of Umberlee, they lost interest once they had defeated it. For some reason - probably only because the program was new - they kept coming back to Dawn Titan, demolishing it in several creative ways and reaping most of the available awards.
One player brought up the Pixie Music Box, an incautiously written quasi-magic item for Heroes of the Feywild. I told him if he wanted to put himself down for "Island of Dreadfully Easy" he could, but I wasn't going to bother running through that. So, they proceeded without that particular trick. The took a lot of boxes and a couple of turrets and stacked them completely around hyacinth. They popped a Hunter's Mist around her, and the pacifist cleric initiated a Stream of Life with her.
I switched up the monster/dino assignments, having the waves come in descending order of speed, and swapping the Storm Sorcerers with the Reavers, so they were on flying dinos and showed up first. I had them approach from wall side of the map. The players hadn't placed anyone/thing on the towers, so I had the casters disembark on the towers, and the pterodactyls start trying to snatch PCs and drop them in the tar, while the. The casters dropped their AEs on the square above Hyacinth, destroying most of the boxes and damaging a turret. There others arrived in waves, Tricertops, then minions, finally anklysaurs.
With Hyacinth in a Stalker's Mist, I damaged her mainly with the few AEs the orcs and dinos had, including the casters' bloodied re-charge. At the top of the 4th round, the Cleric decided to re-vive the Wizard rather than topping off Hyacinth, and I manage to beat her down with the anklysaurs' AEs, a lucky shot or two and a Savage Demise from a Pummeler before the end of the round.
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Second session, the party layered Stalkers Mist and a Warden Power that created cover (somethingorother Life) around Hyacinth, and healed her more thoroughly.
I varied the approach and tactics (the Casters stood off at 30 altitude and dropped lightning for the first round or two). And stopped attacking Hyacinth in round 4 so she'd start round 5 at full hps (it was debateable whether damage carried over from her to the T-Rex, but I thought it'd be fun if it theoretically did, and the party's 'success' meant facing a full-power T-Rex).
One PC died (dropped in tar), but they kept Hyacinth alive long enough to turn into a T-Rex. They quickly bloodied the other Dinos which fled, and beat down the T-Rex with some difficulty but no further fatalities.