Obelisk

The effect of Obelisk is as follows


You must Tribute 3 monsters to Normal Summon this card (you cannot Set this card). The Normal Summon of this card cannot be negated. When this card is Normal Summoned, Spells, Traps, and Effect Monster effects cannot be activated. This card cannot be targeted by the effects of Spells, Traps or Effect Monsters. If this card is Special Summoned, it is sent to the Graveyard during the End Phase. You can Tribute 2 monsters to destroy all monsters your opponent controls. This card cannot declare an attack the turn this effect is activated.

my question is on the bolded part, It was my impression that that effect lasted as long as Obelisk was on the field, am I right or not?

No that only applies when he is summoned, meaning his summon cannot be chained to. After he has been successfully summoned effects/spells/ and traps may be activated. Effects of existing face-up effects/spells/ and traps are not negated, but will not effect Obelisk if they target.

okay then I understand

thanks