I was wondering whether the immortal of thunder's 5000 damage effect can be negated with something like des wombat or trap of board eraser or if it can be redirected by barrel behind the door.

The button with the word "Search" is your best friend...

The Immortal of Thunder does NOT inflict "damage" in any way. It only makes the player "lose" 5000 Life Points, which is completely different.

Des Wombat, Barrel Behind the Door, Pikeru's Circle of Enchantment, Trap of Board Eraser, etc ONLY stop "damage" to Life Points.

Why is this card still questioned about? I has been answerd so many times that it is ridculous. From my knowledged there is no way to redirect the damage to your opponent. Case Closed.

Ok! All the frustratution has been released now over the topic on this card.

It's because a lot of players don't learn terminology of the game, so they always think one thing = anything similar...which is why people think this works...to them...ANY form of your LP dropping is "damage" to them...or ANY card going from your hand to the Graveyard is "discarding" and such...only way they mix is if the card specifically says so (like Bottomless Trap Hole says "Destroy AND remove from play")

Discard = Discard
"Sent from hand to Graveyard" =/= Discard
"Destroyed" =/= Discard
"Tributed" =/= Discard

Destroyed = Destroyed
"Tributed" =/= Destroyed
"Sent from field to Graveyard" =/= Destroyed
"Removed from Play" =/= Destroyed

Damage = Damage
"LP Payment" =/= Damage
"Decreasing LP" =/= Damage
"Losing LP" =/= Damage
"Making LP <number>" =/= Damage

...and so on and so forth.