Spells can let you get guys onto the table, make your guys better, alter the rules of the game or interact with your opponents spells. Each spell has a cost
Cards like Sling-Gang Lieutenant and Pashalik Mons turn dying goblins into damage, while outlets like Skirk Prospector and Goblin Bombardment trade extra bodies for mana or removal
Lands (16) Spells (44) 4 Brainstorm 4 Vampiric Tutor 1 Mystical Tutor 2 Yawgmoth's Will 4 Mana Vault 4 Dark Ritual 1 Megrim 4 Memory Jar 4 Defense Grid 4 Tinker 4 Mox Diamond 4 Lotus Petal 4 Lion's Eye Diamond Sideboard Like all of the most broken decks in Magic history, it featured two Yawgmoths Wills, because there was plenty of time to find one you know, later in your first turn
You can, and many players do
If you set up favorable attacks with combat tricks or falter effects to ignore certain blockers, Raph can be a huge source of additional mana
Being able to find 6 of them in the same limited environment is however going to be a very rare occasion