(Improved) Invisibility and detection is.
Reload metgaming garbage. Who bothers to waste a spell slot on detect invisibility or invisibility purge on the off-chance that you'll run into a wizard who casts it?
Spell protections - Minor Glove of Invulnerability is in (and used by a fair amount of enemies).
Minor Arcane Reflection – Spells are deflected back to the caster.
Elemental protection spells are in.
Bulwark Against The Elements – increases the caster's damage threshold for burn, freeze, corrode and shock.
Fire Shield – Increases the freeze damage threshold of the caster and inflicts burn damage to any enemy that hits the caster.
Woodskin – Creates a thick layer of bark over allies in the area of effect, affording them a Damage Threshold bonus to Pierce, Burn and Shock.
Seven Men, Onto the Deck They Went – Allies in the area of effect gain a bonus to Freeze and Shock Damage Thresholds, and a bonus to defense against the Prone affliction.
Not Felled by Axe, Nor Broken by Storm – Increases allied Slash and Shock Damage Threshold.
Paralysis, Charm, Hold Monster, Web, Horror etc etc are very much in, as are Remove Paralysis, Resist Fear, Chaotic Commands, Free Action, and so on. Dispel Magic is in.
Paralyzed
–40 Deflection
–40 Reflex
–100 Dexterity
Chanter At the Sound of His Voice, the Killers Froze Stiff
Cipher Mental Binding
Druid Hold Beasts
Wizard Arkemyr's Capricious Hex
Fetid Caress
Charmed
–25 Melee Accuracy
Alliance flipped
–25 Will
–25 Deflection
–25 Reflex
–25 Fortitude
x0.75 Attack Speed
–25 Ranged Accuracy
Chanter The Lover Cried out to the Beloved, "I am Yours!"
Cipher Ringleader
Whisper of Treason
Druid Charm Beast
Dominated
Alliance flipped
Cipher Puppet Master
Ringleader
Stuck
–20 Deflection
–20 Reflex
–5 Ranged Accuracy
–5 Melee Accuracy
–2 Dexterity
Immobilized
Cipher Mental Binding
Priest Halt
Ranger Binding Roots
Frightened
–2 Dexterity
–2 Resolve
–10 Melee Accuracy
–10 Ranged Accuracy
Barbarian Barbaric Yell
Chanter Lo, Their Endless Host, the Harbingers Doom
Cipher Tenuous Grasp
Secret Horrors
Druid Venombloom
Priest Divine Terror
Terrified
Barbarian Barbaric Shout
Chanter Reny Daret's Ghost Spake, "I'll Catch You, Ben Fidel"
Druid Nature's Terror
Wizard Ryngrim's Repulsive Visage
Ryngrim's Enervating Terror
Arcane Dampener – Suppresses all beneficial effects to all enemies in the area.
Prayer against Fear – Grants a bonus to resist any attack containing the Frightened or Terrified afflictions. If those afflictions are already on the target, their durations are reduced.
Suppress Affliction – Hostile Effects are suspended for a short duration.
Prayer against Infirmity– Grants a bonus to resist any attack containing the Weakened or Sickened afflictions. If those afflictions are already on the target, their durations are reduced.
Prayer against Restraint – Grants a bonus to resist any attack containing the Hobbled or Stuck afflictions. If those afflictions are already on the target, their durations are reduced by 10 seconds for Hobbled or 5 seconds for Stuck.
Prayer against Bewilderment – Grants a bonus to resist any attack containing the Dazed or Confused afflictions. If those afflictions are already on the target, their durations are reduced.
Prayer Against Imprisonment – Instills a spirit of liberation in allies in the area of effect, granting a bonus against attacks with Paralyzed or Petrified afflictions and reducing the duration of any such afflictions currently on the target.
Prayer Against Treachery – Galvanizes the devotion of the party, granting bonuses against attacks with Charm or Dominate afflictions as well as reducing the duration of any such afflictions already on the target.
Liberating Exhortation - Commands an ally to temporarily ignore existing hostile effects for a short duration. After a short duration, the effects resume with the duration they had before they were suspended.
One Dozen Stood Against the Power of the Saint – Decreases the duration of and defends against Frightened and terrified on allies.
Shatters their Shackles, Cast of their Chains! – Decreases duration of and defends against Hobbled, Petrified, Stuck and Paralyzed.
Yeah, you can't be completely immune to anything. Too bad. High-level D:OS is a pretty good example of why that's a bad thing, and they agreed as far as player characters go, patching it out themselves.
Of course BG1 is not the best thing to fully emulate, Dispel Arrows for example ease the game way too much. If you want the best possible game, you don't directly emulate that but take BG2 and bring its concepts to a lower level environment.
In the history of D&D no one has ever tried to do that despite the grognards' love of godking spellcasters, because it's a bad idea.