Five Spells That Are Too Good Not to Have Prepared

The nature of spell casting in Dungeons and Dragons is such that there will never be a single best spell*. A lot depends on the situation of the moment and spells are very limited in their purview. Sleep is perfect for when you're surrounded by goblins but pretty useless when being attacked by skeletons or drowning in a flooding chamber. That being said there are some spells that are so good that not preparing them is almost silly. What follows are one DM's picks of five, a mix of Cleric and Wizard from the first level list provided in the starter set and basic rules PDF. Feel free to agree or disagree in the comments.

*Except of course for the ever elusive Wish.

5)Shield (wizard): In previous editions Shield was the poor man's Mage Armor. It's limited duration and relatively low bonus to AC combined to make it relatively unattractive despite the fact that it blocked Magic Missile. So what's changed?  In fifth edition certain spells, including Shield, can be cast as a reaction,  meaning that the spell is actually cast in an opponents turn when triggered by another action in this case being hit by a successful attack. This means that you don't have to use the spell slot until you know you're going to need it because the enemy just flung a magic missile at you or hit you with an attack. Plus if the DM is rolling in the open or telling you what his attack rolls are you know whether the spell will make a difference and can choose not to waste the slot.

4) Burning Hands (wizard). Burning Hands has always been sort of the hipster equivalent of Magic Missile, the first level attack spell you take just to be contrary to the accepted wisdom or because your character happens to have a bad case of pyromania. In fifth edition the improvement of Shield has made Magic Missile less effective locking the two spells in a kind of arcane detente.  In this environment Burning Hands really shines. Shield offers no protection against it (nor armor for that matter) and it has the potential to cause more damage if spread over multiple targets.

3) Healing Word (cleric): Healing Word not only allows you to heal damage on a target at a distance (60 feet) it is also a bonus action. This means that after casting it you can cast a cantrip with a casting time of 1 action or make another action (such as an attack or a disengage). Though it doesn't heal as much as Cure Light Wounds, it's a great way to beat the old problem of the cleric not getting to do anything in combat but buff. The third level version (Mass Healing Word) is even better as it allows you to heal more than one companion at a time.

2) Guiding Bolt (Cleric): This has got to be one of the best spells ever designed for any edition. Not only does it have a range of 120' (better than the max range of a hand crossbow) it requires no material components and does 4d6 radiant damage...at first level. But wait there's more! In addition to all of that, the first attack against the target gets advantage, effectively doubling it's chance of a hit. Time it just right and a rogue can use that advantage to add an extra d6 from sneak attack. It does require an attack roll to hit but you should have a more than decent shot of pulling it off.

1) Ray of Frost/Sacred Flame (wizard/cleric): I've cheated a bit and lumped these two together since they are essentially the same spell. Ray of Frost requires a ranged attack and imposes a movement penalty whereas Sacred Flame can be avoided with a Dexterity save, but both spells cause the same amount of damage (d8). They also share a 60' range and neither requires any material components that can be lost or taken away. Both are cantrips so they can be cast at will and in addition to a spell cast with a bonus action. They also increase their damage automatically as the character raises in level whereas every other spell must be cast using a higher level spell slot to do more damage. These factors combine to make Ray and Flame the most reliable way for the wizard or clerics to keep pace with the fighters extra attacks and the rogues sneak attack ability at higher levels.