I want to know something about the Terrorking Archfiend and Desrook Archfiend. Let's say i revive my Terrorking with my Archfiend's Roar. Then, at the end of the turn, my terrorking is destroyed. Can I discard my Desrook to bring back my Terrorking? Is it allowed?

here are the effects:
Terrorking Archfiend
(Dark/Fiend/4/2000/1500)
You cannot Normal Summon or Flip Summon this card unless you have an Archfiend Monster Card on your side of the field. The controller of this card pays 800 Life Points during each of his/her Standby Phases (this is not optional). When this card is specifically designated as a target of the effect of a card controlled by your opponent, when resolving the effect, roll a six-sided die. If the result is 2 or 5, negate the effect and destroy the opponent’s card. Also negate the effect of an Effect Monster that is destroyed by this monster in battle.

Desrook Archfiend
(Light/Fiend/3/1100/1800)
The controller of this card pays 500 Life Points during each of his/her Standby Phases (this is not optional). When this card is specifically designated as a target of the effect of a card controlled by your opponent, when resolving the effect, roll a six-sided die. If the result is 3, negate the effect and destroy the opponent’s card. When a “Terrorking Archfiend” on your side of the field is destroyed and sent to the Graveyard, you can send this card from your hand to the Graveyard to Special Summon the “Terrorking Archfiend”.

Archfiend’s Roar
(Trap)
Pay 500 Life Points to activate this card. Special Summon 1 Archfiend Monster Card from your Graveyard. This monster cannot be offered as a Tribute under any conditions and is destroyed during the End Phase of this turn.

Last I checked, that was still a legal move. So, unless something changed or there's something I'm not taking into account, yes, you can discard Desrook Archfiend from your hand when Terrorking Archfiend is destroyed by the condition placed on it by "Archfiend's Roar".