I think that Obelisk will be given by the duellists forced to complete 4 Challenges:
1. Defeat Seto Kaiba At Lv 30
2. Defeat Ishzu Ishtar at Lv 30
3. Defeat Maximillion Pegasus at Lv 30
4. Summon both Ra and Slifer in one duel.
This card is strange, it is another signature card of Kaiba, but none had mentioned its effect. It is ATK 4000(fixed) monster. Will it be only normal monster with ATK higher than BEWD or with some immune effect?
there are no cards with "infinite attack". obviously stuff in the manga and anime will be twisted dude. tho theoretically some cards could get to 40,000 attack. but it would never happen in a real tgc match.