2nd WORST EXPERIENCE on my first COPPER CITADEL

Just 15/20 mins ago i found my first CITADEL (Copper) after 200++hours im lvl 92 Monk , i get through just fine....until i fought the Boss (EASY) but thn, because im Monk i need to be close,,I DEFEAT THE BOSS and FVKING BOOM!!!!!! MAP COMPLETED - I DIED - THE DROP GONE!!!!!!!

HOW ON EARTH???DO WE SUPPOSE TO KNOW THAT THE BOSS WILL BLOW UP AT THE END OF HIS LIFE?????????????????????????????????????????????????

I LOST MY LOOT (dozen of it!!!!)
I LOST MY EXP
CAN'T REPEAT THE DUNGEON TOO!
and what do i get in return??? EXPERIENCE?????????
The Game mechanic is bad, no explanation whatsoever.
WORST ANIMATION on INSTANT DEATH ATTACK , u cant even see it on some map due to lack of color or else.

I wont bother if i died because of the Boss/Mobs mechanic, but because of something i didnt see or BLOWN UP BOSS??? HOW THE FUCK?

Tell me your worst experience, so i can be at peace.

I believe this was specifically mentioned in the 0.1.1 interview and they are addressing it in the upcoming patch.

That key cost 2 divines because is bugged, it'll be fixed in upcoming patch they said