How can my Bladesinger Wizard ensure that their spells cannot be avoided?

Question

I have been playing a Bladesinger wizard in a fairly long running campaign, at least by my standards. There have been a lot of good moments but after my third attempt to make disintegrate work, I have realized something: everything worth using a big spell on probably has a good enough save that the big spell won't work.

Obviously, I don't like that, so I have come to ask, what ways can a wizard use spells that are guaranteed to have at least some effect?

The suggestions are ideally achievable by 15th level, since that is the goal of the campaign,and should not require more than a dip into another class, hopefully keeping pure wizard. I have already picked the bladesinging school and am looking for spells in general.

Our party includes a Grave Domain Cleric, a Fighter, a Barbarian, and a Rogue/Warlock.

Answer 1

Avoid "all or nothing" spells, especially against boss type enemies.

By "all or nothing", I'm referring to spells, like Disintegrate, that have zero effect on a creature that saves against them. These spells are especially risky against bosses that tend to have high saving throws and/or Magic Resistance, and may have Legendary Resistances to save themselves even if they roll poorly.

Instead, consider spells like Fireball, Wall of Ice, or Sunbeam that deal half damage even if the target saves. Or, there are a few rare spells like Otto's Irresistible Dance or Power Word Pain that don't offer an initial save and just work initially but give the target a chance to save once they've experienced the effect for at least a turn.

Spells that use attack rolls, like Scorching Ray, Steel Wind Strike, or Crown of Stars can also be more effective, depending on the situation. Many enemies that have great saving throws don't necessarily have a great armor class, and attack roll based spells don't have to deal with Magic Resistance (which grants advantage on saving throws vs spells) or Legendary Resistances.

Alternatively,

Don't blast your enemies, buff your friends (or yourself)!

Unless all your enemies are equipped with Counterspell, you never need to worry about a buff failing. Spells like Enlarge/Reduce (choosing Enlarge), Haste, or Greater Invisibility cast on yourself or the party's Fighter, Paladin, or Barbarian can help them tank or dish out more damage. Fire Shield, Blink, and Mirror Image are some nice spells to help with your own survivability, and none of them even require concentration.

And,

Control the Battlefield.

Create difficult terrain to keep enemies from moving as they please with spells like Earth Tremor, Erupting Earth, or Ice Storm. Cut off enemy lines of sight with spells like Fog Cloud or Darkness. Block enemies' paths or lines of sight to your allies with the various "Wall of ..." spells. Use Telekinesis or Bigby's Hand to hold an enemy in place (these spells both use contested ability checks instead of saving throws, so you can bypass Magic Resistance and Legendary Resistances) or move aspects of the terrain.

Answer 2

Depends on the Save

There are very few ways to automatically ensure a target fails a save. There are more options for increasing the likelihood of failure. But you should be aware that there is no counter to Legendary Resistances short of forcing them to be burnt through. Save or die is pretty much non-existent in 5e and Legendary Resistance is there to reinforce that.

Strength & Dexterity Saves

Failure on either of these saves can be guaranteed by imposing any of the following conditions on the target: Paralyzed, Petrified, & Stunned.

Of those three, the most available to you as a Wizard is either Paralyzed or Petrified. Paralyzed is best accessible to you via the Hold Person and Hold Monster spells, both of which can be upcast to target additional creatures. As a 2nd or 5th level spell, respectively, you can attempt casting it multiple times in a day.

Flesh to Stone is the best means to access the Petrify effect, but as a 6th level spell it's probably much less useful to you. Furthermore, once you petrify the target it's really not necessary to do anything additional.

Constitution, Intelligence, Wisdom, and Charisma Saves

There is no way to force a creature to fail these saves besides NathanS's answer. But there are several things that you can do to set the stage with the team you have available (which I suspect is by design).

Your Grave Domain Cleric can impose a 1d4 penalty on an opponent's save by using the Bane spell. Given that success on a non-proficient save is often by only a point or two (even with advantage) this is big deal.

You or the party Warlock (if they took the appropriate invocation) can cast Bestow Curse on the target to force Disadvantage on saves with the preferred ability score.

Use Spells That Don't Allow Saves

Since you're in the realm of 6th level spells and up, there are a few spells you have available which don't grant saves at your disposal.

• Otto's Irresistible Dance
• Power Word Pain (which can be useful for setting up saving throw failures on anything but Constitution)
• Reverse Gravity (this allows a save to keep yourself from flying up, but if it's centered on you and you don't have a fly speed you're probably going to be stuck where you're at)
• Maze
• Power Word Stun

Use Spells That Give You Lots of Chances (or rely on attack rolls)

It is way easier to up your odds of hitting the opponent by finding situations to give yourself advantage on attack rolls. Also, if one spell gives you multiple opportunities to inflict severe conditions on an enemy, then they're very useful. Consider the following:

• Eyebite
• Sunbeam
• Crown of Stars

Answer 3

Heighten metamagic

If you take 3 levels of sorcerer, you can impose disadvantage on a save by spending 3 sorcery points. You can regain these points for a 3rd level spell slot, so you can use this quite a few times per day.

Otto's Irresistible Dance

This spell has an effect with no save allowed. The creature can then take an action on their next turn to try to end it, but that is also depriving them of their action, so you win either way.

Forcecage

This spell doesn't allow a save, and traps a creature for 1 hour. If they have teleportation magic they can save to escape, but if they don't there is nothing can do to escape (well, except for casting disintegrate).

Answer 4

Although you've mentioned in your question that you've already picked the Bladesinger subclass, for others looking for answers who do not have that restriction (i.e. the restriction of having already chosen their subclass):

Be a School of Divination wizard

As a School of Divination wizard, you have access to the Portent class feature (PHB, p. 116):

Starting at 2nd level when you choose this school, glimpses of the future begin to press in on your awareness. When you finish a long rest, roll two d20s and record the numbers rolled. You can replace any attack roll, saving throw, or ability check made by you or a creature that you can see with one of these foretelling rolls. You must choose to do so before the roll, and you can replace a roll in this way only once per turn.

Each foretelling roll can be used only once. When you finish a long rest, you lose any unused foretelling rolls.

At 14th level, you would also have Greater Portent:

Starting at 14th level, the visions in your dreams intensify and paint a more accurate picture in your mind of what is to come. You roll three d20s for your Portent feature, rather than two.

So, depending on what you roll for your portent dice for the day (so this isn't totally guaranteed), you can force a creature's saving throw to be a very low number. At 15th level, as you mention in your question, you have three shots at rolling super low number for your portent dice for the day.

They will still be able to add their modifier to that saving throw (including their proficiency bonus if they are proficient in that saving throw), but if the number you replace their roll with is sufficiently low, and your DC is as high as you can get it (using your ASIs to max out Intelligence), then even a large saving throw modifier won't save them. That said, if the creature uses Legendary Resistance, that will still foil Portent.

If you roll super high numbers on your portent dice (ideally a natural 20), this will also work in your favour for using spells that use spell attack rolls instead, likely beating the AC of most "boss monster" creatures (again, assuming you prioritise Intelligence to get the largest spell attack bonus modifier you can get, since portent only replaces the number you roll on the die).

Answer 5

You don't get to use a single spell to make a serious challenge for a party of 4 equal-power adventures lose the fight.

Monsters get high and increasingly strong saves and legendary resistances. They get bigger (nullifying a number of suck moves that work on smaller targets), and have more veto abilities (like teleports).

To beat them with spells that involve saving, you have to shoot volleys of "this would be bad if I didn't save against it" spells from every party member, and ideally from summons as well, with as high save DCs as you can pull off.

The goal is to deplete the monster's legendary resistances, or to simply land an annoying condition through sheer luck.

There are level 1 spells that are nasty enough that a monster wouldn't want to be subject to them -- faerie fire, bane, hideous laughter for examples.

A non-wizard can Conjure Woodland Being, then have 8 pixies all cast polymorph (turtle) on the enemy. If their wisdom save is less than +11 this has a pretty good chance of nullifying the foe's offence or eating a legendary resistance or two. An adult red dragon has a +7 wis save; they need a 5 to save. With 20% failure chance per pixie, that is 1.6 legendary resistances burned per cast of Conjure Woodland Being. (Being a turtle doesn't win the fight, but it is pretty close.)

As the party barrages the foe with things to eat legendary resistances, you'll get a better idea of what saves aren't insanely good. You'll want a collection of "save or suck" spells that target 4 to 6 different stats prepared.

Then you can start dropping those on it, focusing on its weakest stat. Usually the spell will fail, but a repeated 30% chance to win fight is a pretty strong move.

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Another approach is to give up on save-or-suck spells. Defending and increasing the offense of your party is a tried and true way to win.

There are a handful of spells that don't rely on saving throws. Irresistible Dance burns an enemy action regardless of what they do (and possibly a legendary resistance). Force cage is a no-save no-concentration spell.

On a large or smaller creature, a warlock/sorcerer/wizard casting sickening radiance followed by a readied force cage is a "you lose" spell combo (please succeed at 95 out of 100 con saves at cleric spell save DC or die); if they are a spell caster, adding silence (requiring a 3rd spell caster) finishes the deal (a high level fighter-bard can do this themselves, which is gross: bard 18/fighter 2 does wish:simulacrum, double action surge, silence, sickening radiance, forcecage).

Answer 6

While this doesn't help you specifically (you added that you were a bladesinger after I posted) it is how I solved the issue for my Wizard.

Wizard School of Chronurgy magic (EGTW p184) Offers you a few features that help.

LV 2 Chronal Shift:...As a reaction, after you or a creature you can see within 30 feet of you makes an attack roll, an ability check, or a saving throw, you can force the creature to reroll...

LV 14 Convergent Future: ..When you or a creature you can see within 60 feet of you makes an attack roll, an ability check, or a saving throw, you can use your reaction to ignore the die roll and decide whether the number rolled is the minimum needed to succeed or one less than that number (your choice)...