Only spells can be cast while every card type is played. This difference is especially important when looking at cards that allow you to play cards from exile, a function that red cards use in place of draw effects
That's why I'm purposefully misinterpreting the card to let you Tribute off your opponent's Monsters of Horror in hopes of it being more playable
It also reads, Whenever one or more Artifact Creatures you control attack, Alibou, Ancient Witness deals X damage to any target and you scry X, where X is the number of tapped artifacts you control. The best part about this is that it includes any mana rocks or whatever else you have out
You've got options: Online marketplaces (eBay, Facebook, forums) give you reach but have drawbacks like fees, fraud, or flaky buyers
Counterspell Few cards define the best instants in MTG like Counterspell does