At his summon you can't activate any trap(so no trap hole), spell, monster effect... After his immune summon, Obelisk is UNTARGETTABLE, but there are many cards and effects which don't target.
Obelisk can be defeated by the use of blast held by a tribute trap card from isihzu spells and other traps are possible but only for sure take out is blast held by a tribute same if you watched the show but kiaba was smart and used Blue-Eye's white dragon instead of Obelisk to win
Nick
John
