If you're looking for cards you can play in your kitchen table games, you could include of these iconic spells that help counter your opponents strategies. Just be aware that delving too deep into strong, flexible cards like these could kick off an arms race!
White: Oblivion Ring, Wrath of God
Blue: Unsummon, Counterspell
Black: Murder, Distress
Red: Lightning bolt, Abrade
Green: Prey upon, naturalize
That would be another good option. I picked Distress because I thought the flexibility would be nice for beginners but I'm certainly no expert.