Yeah. This is my first real look at it and...What does it even mean?
You "change the nature of the illusion (using the spell's normal parameters for the illusion),..." What does that mean? At 6th level, we're talking about stuff like Invisibility, Mirror Image and Major Image. How does one "change the nature" of these spells? What is "changing the nature" of these spells?
It essentially changes "I can spend one slot, to cast this one illusory effect, and have that effect last up to its duration" to "I can spend one slot, to effectively cast one illusion (
Silent Image, Major Image, etc.) per round for the duration listed on that spell." Your illusory knight gets pegged with an arrow and the gobbos disbelieve? Use an action (no verbal or somatic components necessary) and said useless knight vanishes and a wall of fire appears in another location. And you still have a bonus action to use on
Healing Word or
Misty Step or the like.
Sure, a non-Illusionist wizard can replicate this by recasting the spell...a grand total of as many times as she wishes to waste the spell slots. Illusionists do more with less. Heck, cast
Major Image in a sixth level slot and it's effectively permanent. An 11th level Illusionist essentially has a 3rd level spell at-will, at that point. Sure it takes an action to move around and keep with you, but that's hardly an insurmountable hurdle. Added bonus? Your 3rd level illusion no longer takes up your concentration slot, either, so rock two illusions at once (three with
Minor Illusion) or work on battlefield control with your illusion while maintaining a concentration buff or debuff as well. All while
Disguse Self'd, which comes in handy with Malleable Illusion again, because a) you don't have to recast or b) expose that you're casting (just change your appearance by willing it with Malleable Illusions, no components necessary). Then
Misty Step (at-will when you're a level 18 wizard!) to another location, with another face. Bonus points for impersonating someone else on the battlefield. Or, you know, concentrate on maintaining
Invisibility on yourself. Using Malleable Illusions to change your ongoing spell isn't casting a spell, so there's a good chance it won't break your invisibility, and you're still contributing to the fight while keeping yourself safe.
Take it to the next level. Malleable Illusions + Illusory Reality +
Mirage Arcane. When my Illusionist hits this point, he will be casting
Mirage Arcane outside of every dungeon the party is about the enter. It's a rare dungeon that extends more than a square mile, and 10 days is a long time. With luck, you'll get a long rest in, and have that 7th level slot back as well. Make one minor change with the spell to start. Say, markers on the walls as you go, marking what you have explored. With Malleable Illusions, it's simplicity itself. Keeps the illusion always in sight, provides utility and flavor. Oh no! Pit trap triggered! Malleable Illusions on the
Mirage Arcane plus Illusory Reality to provide the oft cited bridge effect! Additional party resources used? None.
Yikes! Combat erupts! Giant bats you say? Not smart, blindsense...but
Mirage Arcane includes tactile and auditory effects, so these beasts shouldn't automatically see through the stone web cage
Mirage Arcane'd around them. The swarm of subterranean dwellers (duergar, troglodytes, whatever) using the bats as mounts running toward the party? They're crossing difficult terrain (also courtesy of the same
Mirage Arcane action that imprisoned the giant bats). Obvious toughs can be boxed as an action (they may or may not get a dex save, depending on circumstances/tactic and DM judgement call. Fair dues. Not like it's costing you any additional spell slots, right?). Dang. They pulled out crossbows. Guess it's time to spend an action for instant fortifications, with arrow slits, so the party can snipe back from awesome cover? Illusory Reality makes it real for 10 combat rounds. A few dozen more appear, making the odds increasingly bad. Well, if you have to retreat, they can't pursue for a minute or so, and nothing is stopping you from dropping new walls behind you as you flee. It only takes one action for the wall and one bonus action to make it real. Not to mention the terrain in front of the party is smooth going, while behind them it's all difficult terrain. Thanks
Mirage Arcane and Malleable Illusions!
Hrm. Looks like they have a few casters that are intent on following. Hope whatever spells or other abilities being used to bypass those walls are at will, or they are burning a lot of resources just to chase us. Save something for the battle, boys! Still a few coming. Let's see, we have about a half-mile range that can be fiddled with...how about a chute going about that far, with a trap door over it? They did take the time to cast Truesight...so it's a DM call whether or not they can see illusion made real for what they truly are. In either case, if they don't have good Dex and/or Perception, they might take a trip down, fast. Somehow or other, however, the party escapes, finding themselves deep within the dungeon, in...
THE LAIR OF THE LICH
Little spellcasting bugger has Truesight naturally, too. This would totally be a nasty, tough fight, particularly with the Lair abilities in play. Illusory Reality becomes more important here, using actions to try and trap the lich, or to provide cover for you and the party. Truesight shouldn't be able to see through things made real with Illusory Reality. It's also very possible to lose
Mirage Arcane to a
Dispel Magic. (Good time to break out your
Counterspell!) But every time you can use an action to cost the lich a spell slot is a gain, especially if it also keeps the party from taking a direct attack. It isn't draining party resources, and it isn't like the Illusionist isn't still all but full up on other spells with much less debatable effects.
And don't forget that through all of this you also have a permanent, non-Concentration
Major Image along for the ride, too.
My only real gripe with the Illusionist is that it seems much better as a Charisma based caster, with lots of Deception in there for the synergistic effect.
But that's the thing right there with Illusionist School abilities. They are wonderfully synergistic. Don't take them as stand alone pieces, look at the picture as a whole.
Sorry, this is my first post and I LOVE illusions and illusionists. Might have gotten a bit carried away.
