This large warning appears on any trigger-marked page, except if you follow certain direct links from elsewhere on my website.
(I make sure my intra-site links are already marked with the trigger warning, so the extra message would just be inconvenient.)
On the left side:
The seven students to be killed are standing around in a large dungeon room, talking amongst each other, when Draco and Luna peek in the door with wands out. Some of the students notice them, others don't. The room has a tiled stone floor and dark walls with hexagonal pillars built into them.
Draco and Luna step into the room. DRACO AND LUNA: Avada kedavra!
Pansy Parkinson and Graham Montague die before they can react.
Draco and Luna continue advancing and casting Killing Curses. Crabbe tries to pull out zir wand, but is too slow. Daphne Greengrass casts a shield spell, but Luna's curse blasts right through the shield.
On the right side of the page:
Harry steps into Dumbledore's office, with zir wand clenched in zir fist.
PRESENT HARRY: It had been four years since the day I promised myself to kill him...
Dumbledore starts to step from behind zir desk.
DUMBLEDORE: Ah, Harry, I confess th–
PAST HARRY: Stupefy!
PRESENT HARRY: I had been so young, I felt... And yet...
Dumbledore is blasted backwards by the spell, and for the first time, we see zir whole face, which is heavily lined and surrounded by a thick mane of white or grey hair. Dumbledore collapses on the floor in front of zir desk and Harry, now drawn as a silhouette, stands over zem. Harry is pointing zir wand down at Dumbledore.
PRESENT HARRY: I would not break the trust of myself...
The Stunning Spell is supposed to knock the target unconscious. It didn't work completely, not because Dumbledore has any special immunity the way Luna does, but because Harry isn't very good at magic.
In the room on the top left, from left to right, those are Zabini, Crabbe, Millicent Bulstrode, Charles Warrington, Daphne Greengrass, Pansy Parkinson, and Graham Montague. We've seen Daphne Greengrass and Graham Montague before - they were the two students bullying Harry in McGonagall's class on page 8. And of course we've seen Zabini and Crabbe before.