FrogReaver
The most respectful and polite poster ever
Sorry for the long post. I wish there was a way to make smaller tables. Oh well.
Anyway, here's the list. A few spells have question marks (?) as I'm still debating but you get the idea. So your job is to find 2-spell combos that could be a problem or broken. Thanks!
Spell Level Type Friends Cantrip A Guidance Cantrip A Resistance Cantrip A Bane 1st E Bless 1st A Compelled Duel 1st E Detect Evil and Good 1st A Detect Magic 1st A Detect Poison and Disease 1st A Divine Favor 1st A Entangle 1st E Expeditious Retreat 1st A Faerie Fire 1st E Fog Cloud 1st E Heroism 1st A Hex 1st E Hunter's Mark 1st A Protection from Evil and Good 1st A Shield of Faith 1st A Silent Image 1st E Tasha's Hideous Laughter 1st E Alter Self 2nd A Beast Sense 2nd A Blur 2nd A Calm Emotions 2nd E Cloud of Daggers 2nd E Crown of Madness 2nd E Darkness 2nd E Detect Thoughts 2nd A Enhance Ability 2nd A Enlarge/Reduce 2nd A/E Flame Blade 2nd E (?) Flaming Sphere 2nd E Gust of Wind 2nd E Heat Metal 2nd E Hold Person 2nd E Invisibility 2nd A Levitate 2nd A/E Locate Object 2nd A Magic Weapon 2nd ? Moonbeam 2nd E Pass without Trace 2nd A Phantasmal Force 2nd E Silence 2nd E Spider Climb 2nd A Spike Growth 2nd E Suggestion 2nd E Web 2nd E Aura of Vitality 3rd A Beacon of Hope 3rd A Bestow Curse 3rd E Clairvoyance 3rd A Conjure Animals 3rd E Crusader's Mantle 3rd A Elemental Weapon 3rd ? Fear 3rd E Fly 3rd A Gaseous Form 3rd A Haste 3rd A Hunger of Hadar 3rd E Hypnotic Pattern 3rd E Major Image 3rd E Protection from Energy 3rd ? Sleet Storm 3rd E Slow 3rd E Spirit Guardians 3rd A Stinking Cloud 3rd E Vampiric Touch 3rd ? Wind Wall 3rd E Arcane Eye 4th A Aura of Life 4th A Aura of Purity 4th A Banishment 4th E Compulsion 4th E Confusion 4th E Conjure Minor Elementals 4th E Conjure Woodland Beings 4th E Control Water 4th E Dominate Beast 4th E Evard's Black Tentacles 4th E Giant Insect 4th E Grasping Vine 4th E Greater Invisibility 4th A Locate Creature 4th A Otiluke's Resilient Sphere 4th E Phantasmal Killer 4th E Polymorph 4th A Stoneskin 4th A Wall of Fire 4th E Animate Objects 5th E Antilife Shell 5th A Bigby's Hand 5th E Circle of Power 5th A Cloudkill 5th E Conjure Elemental 5th E Dispel Evil and Good 5th A Dominate Person 5th E Hold Monster 5th E Insect Plague 5th E Mislead 5th A Modify Memory 5th E Scrying 5th A Swift Quiver 5th A Telekinesis 5th E Tree Stride 5th A Wall of Force 5th E Wall of Stone 5th E Arcane Gate 6th E Blade Barrier 6th E Conjure Fey 6th E Eyebite 6th E Find the Path 6th A Flesh to Stone 6th A Globe of Invulnerability 6th A Move Earth 6th E Otto's Irresistible Dance 6th E Sunbeam 6th E Wall of Ice 6th E Wall of Thorns 6th E Conjure Celestial 7th E Delayed Blast Fireball 7th E Mordenkainen's Sword 7th E Project Image 7th E Reverse Gravity 7th E Animal Shapes 8th A Antimagic Field 8th E Control Weather 8th E Dominate Monster 8th E Earthquake 8th E Holy Aura 8th A Incendiary Cloud 8th E Maze 8th E Tsunami 8th E Gate 9th E Shapechange 9th A Storm of Vengeance 9th E True Polymorph 9th A Weird 9th E
Something like Hypnotic pattern followed by a twinned haste could be really potent and is a combo available at level 5+. There's a number of other similar combos.
A strong early game combo might be something like bless + bane.