8 Powerful Enhancement Spells ended by Very Trivial Things

You could also called this "Eight Buff Spells" but some people get butthurt when you use video game terminology in tabletop games even when their origins are in tabletop in the first place.

[1] Mine Eyes of Iron
This spell turns the caster's eyes into iron balls, with no loss of sight or health. This spell has multiple effects. Firstly, the eyes become nearly immune to damage. Eye pokes, with weapons or fingers, become ineffective and no longer blind the Iron-Eyed target. Second, any flare or bright-light spells meant to blind the user of this spell instead have it reflect off the eyes and back at the caster who sent the spell. Finally, the "iron eyes" also refers to what you "see" with this spell. While your eyes are replaced with iron, scenes of depravity, torture, shocking violence, or even sanity draining effects have no effect. You can stare a Medusa or Basilisk straight in the face without being turned to stone or dying from it; your eyes are immune to their deadly magics.

This spell ends and the caster's eyes return to normal the next time the caster cries.

[2] Bulging Power
The caster or one target they touch instantly becomes morbidly obese for their species. This has the effect of raising their Constitution temporarily by +1d4 points, (in my game, higher CON grants bonuses to AC, so grant +1d2 AC to this spell as well if you don't) as well as increasing the elasticity of their equipment so it folds around their folds.

However, this weight is not the same as real, regular fat. Instead it is buoyant, nearly weightless for them, granting them a feeling of lightness. For everyone else, it's just as heavy as regular fat. They can step, run, or leap at almost the same speed and height as they could before, with all the momentum of a blubbery cannonball. Slamming into someone the same size as you or smaller now deals 1d3 damage and knocks them down. Also, while under the effect of this spell, you get +10% magic resistance - ignoring 1 out of every 10 spells, stacking with your other magic resistance if any.

The spell ends if you go one turn without eating a meal, or if you run for more then two or three rounds consecutively. Retreating from a battle will always end this spell early.

[3] Archaic Strength
The caster or one target gains a sudden surge of primeval strength. Their muscles pump up with powerful veins, hairy sprouts from their body, and their teeth and jaws become stronger. They physically shift to appear similarly to an ancestor might have in the distant past; humans will become like cavemen, birdpeople will look more like dinosaurs, etc.

While under the effect of this spell, the target treats their Strength modifier as +3 and can run, jump, and climb roughly 50% faster, higher, and better. They also gain some resistance to environmental extremes; turning a blazing desert into just a sunny day for them, and while wearing just rags or a loincloth they'll be as warm as a normal person wearing a heavy warm coat; but this has no effect on elemental magic.

This spell ends when the subject of the spell sleeps indoors OR consumes anything created as a result of agriculture and civilization. Meat and berries are fine; grains, bread, beer, potions, etc. are not.

[4] Sleeper's Ohel
This spell must be cast on a person who is asleep, or conjunction with Sleep on a willing target. Casting this spell this way uses up the prepared Sleep spell in addition to this one.

Once the sleeping person lays down, a magical structure is erected around them from local materials- iron, wood, and stone will all grow and twist to become a small building around the sleeping person. The building has the space to hold up to four other adult humans in terms of size, but is quite cramped. There are no windows and a simple stone doorway. The doorway is open to the air but covered in a layer of shadow- you can see out but nobody can see in. You can press up against the walls to have a 1 in 3 chance of avoiding anything being thrown or fired outside the tomb through the doorway. Additionally, damaging the Ohel from outside it will cause it to start to repair itself magically; it would take at least 3 people with crowbars or mining picks to break a wall down faster then it can fix itself.

While within the Ohel, the "sleeper" of the spell is immune to all opposing spells and is hidden from sight from magical abilities like sensing or scrying- the stone structure essentially become opaque even to magic eyes. Everything within the structure receives the same protection, as long as they remain within the Ohel. Nobody opposed to the sleeper is allowed may step foot within- and the sleeper is covered in a stone/metal/hardwood "casket" that protects them from enemy fire or attacks.

This spell ends when the Sleeper wakes up. It grants no special protection from noise or sensation; so a simple loud shout or sounds of a battle outside the Ohel can wake them up. If the Sleep spell was used in conjunction with this one, grant the Sleeper an unusually deep sleep equal to the normal duration of the sleep spell. When the spell ends, the Ohel remains upright but loses its magical power and self-repairing ability; essentially making it a tiny, rickety hut.

[5] Goat Mask of Magic & Satans
This spell requires a severed goat head, or at least dried goat skins and old goat horns, to be worn on the user's head when cast. The magic transforms the goat head into a well-fitting goat mask which does not block the user's vision or ability to cast spells. The mask is still clearly a mask, just very convincing.

While wearing the goat mask; the wearer gains powers of magic and satans. Spells involved with summoning demons, spells that deal damage, or spells that cause curses or hexes are all cast as though the caster is a level higher. Additionally, the goat mask wearer can perform a bleating noise that sounds just as a goat's cry; which acts as a "magic word" of activation for most magic items, secret doors, and so on. Finally, the goat mask wearer can tell if someone is evil or not just by looking at them; so if anyone CLAIMS to be a hardcore satan themself, you can tell. You can't tell if someone is neutral to good however, so a paladin would just look like an average dude, but you wouldn't mistake them for evil so heroes can sneak into your forest orgy.

This spell effect ends if the mask is pulled off or if anyone refers to you as anything other then "a satan", such as using a title or name of yours that they know. They can't just call you whatever they want but if they knew you were a bandit leader and using this power they could say "hey it's that bandit leader guy!" and the mask would dissolve because you aren't a cool Satan anymore.

[6] Soldier's Retribution
This spell is cast on a regiment of troops, not on an individual. The soldiers involved in the spell must all be present and willing for its casting- every soldier touches a piece of armor from a fallen comrade fighting for the same cause as they.

Once this spell is cast; any one of these soldiers struck down by an enemy causes a wave of weakness to spread throughout the enemy soldiers- causing them to feel more and more tired as though they had to fight twice as long and hard to kill as many of the blessed soldiers. For every hour of fighting against the blessed battalion, enemy troops are twice as weak or exhausted by the battling.

This spell can be countered by killing the regiment of troops with arrows or artillery.

[7] Dragon King Illusion
This spell is cast on the spellcaster, who must have a genuine piece of dragon bone to cast it. Fake or magically conjured dragon bones don't work- the spell functions but creates them as a hilariously stupid giant stuffed dragon. The "Dragon King" then balances the bone on their head while puffing up and shouting to maximize their presence. This spell consumes the bone and turns it do dust; with larger bones having longer duration.

Once this spell is cast; the caster appears as a towering bipedal dragon, anywhere from 20 to a mile in height- the amount of respect, worship, or fear that the viewer has for dragons determines how powerful or godly the Dragon King appears. This bipedal dragon appears regal, all-powerful, in a fine colorful mist with huge wings and a flaming crown. His voice can boom over an entire town, and can create massive images of fire or destruction. The dragon king's presence is so great that it can even force dragons to pause and stop fighting or force them to listen what he says.

This spell is a pure illusion and is a bubble made of smoke and mist. If an arrow directly strikes the Dragon King's phantasmal body it is destroyed and the spell ended.

[8] Cannoneer's Cant
This spell can be cast on two separate people; the caster putting their hand on each while whispering the incantations. The spell can also be cast on a caster and another person, though the spell must always be cast on two people. Usually, it is cast by a pirate mage on their two best gunners.

Once cast; the spell allows both under its effect to speak in a very precise, quiet, incomprehensible language of pure math, measurements, wind speeds, knots, and powder weights. These two will be able to flawlessly communicate and bolster each other's ability with cannons and ship-weapons. Increase the accuracy with cannons as though firing with advantage, always using the better of the two's dexterity or other scores as a modifier. They also attack faster; if in nautical combat a cannon can only fire once every other round, this allows them to fire once every round, and so on.

This spell ends the moment anyone says anything to them other then something directly related to firing a cannon at something. Like "look out there's a pirate behind you!".