Manticore of Darkness and Horus Lv6

[StRiKe_NiNjA]

If Player1 controls Player2's Beserk Gorilla Snatch Steal, and Player1's Manticore of Darkness is sent to the graveyard, during that End Phase, can Player1 send Player2's Berserk Gorilla to Player2's graveyard and Special Summon Manticore of Darkness from the graveyard?

If Player1 controls Player2's Horus the Black Flame Dragon Lv6, can Player1 send Horus The Black Flame Dragon Lv6 to Player2's graveyard and Player1 Special Summons Horus the Black Flame Dragon Lv8 from his/her deck?

 

[Raigekick]

If Player1 controls Player2's Beserk Gorilla Snatch Steal, and Player1's Manticore of Darkness is sent to the graveyard, during that End Phase, can Player1 send Player2's Berserk Gorilla to Player2's graveyard and Special Summon Manticore of Darkness from the graveyard?

Yes, as long as Player1 send the "Beserk Gorilla" that he currently controls with the help of "Snatch Steal", then "Snatch Steal" will be destroyed by Game Mechanics. It did not say send the monster to YOUR graveyard. It can be send to any graveyard.

If Player1 controls Player2's Horus the Black Flame Dragon LV6, can Player1 send Horus the Black Flame Dragon LV6 to Player2's graveyard and Player1 Special Summons Horus the Black Flame Dragon LV8 from his/her deck?

If you manage to control Horus LV6, and fulfiled his condition to level up, then you may do so. Again, the card said send it to the Graveyard (any graveyard)