This is a take on an “evil genius” build - an assassin that uses magic rather than knives as his weapon. It uses wizard spells and spell-power boosts to augment your abilities as an assassin, and assassin stealth and unique spells to aid you in delivering death as a wizard.  It makes use of every trick we could think of to keep the caster levels up – for instance, it manages to get into Assassin without any Rogue levels! The assassin side allows the wizard side to deliver lethal spike damage if the need calls for it, while the wizard side allows the assassin to contribute to situations where stealth and solo operations aren’t in demand. 

Be advised: The massive tier difference between the wizard and the assassin, and the extreme demands to keep caster levels up, make this build look far more like a wizard than it actually is (except at the earliest levels – think of it as a wizard who becomes an assassin and uses his magic as his implement of death, rather than a pure-blooded rogue/assassin caster). In reality it’s using wizard tricks to augment the assassin side of things, falling back to pure wizardry when that doesn’t work. Really, the best place to look to boost assassin casting turned out to be wizard casting.

Race: Illumian. You’ll be taking the Krau sigil for certain; your other is either Naen or Uur, to taste.

Ability Scores: 8/14/14/18/8/8; Intelligence is bumped at every opportunity.

Alignment: You gotta be Evil to be an assassin. Please, keep these arguments to another thread.

This build uses a little-known feat in the DMG2 to keep your caster level and your stealth skill ranks up; apart from meeting your prerequisites you’re pretty open. Those prereqs mean maxing out Hide, Move Silently, Spellcraft, and Disguise (cross-class) along with 4 ranks in Knowledge (Arcana) and, eventually, Search 8, Spot 8, and Sense Motive 4. Those last three skills can be handled once Search and Spot become class skills as an assassin, though.

Consider yourself a wizard when shopping and you can’t go wrong here. You don’t start out thinking like an assassin until nonmagical gear is essentially free anyway. If you eventually pick up armor as an assassin, remember that ASF still matters to your wizard spells and plan accordingly.

The usual Intelligence, Constitution, and Dexterity boosters, including an Intelligence tome, are pretty much a given. Furthermore, if there are items in your campaign world that add spells known to the assassin, and they are not currently in your possession, I would like to remind you of your Evil alignment and sneaky-sneaky magical powers to rectify that proble (Runestaffs might work once you get Residual Metamagic, but for full effect, you need things like the little-known Explorer’s Handbook’s Drake Helm). Other than that, there are no real standouts: if you have a preferred set of stealth/casting gear, go for it!

1 – Wizard – (Scribe Scroll, Familiar) (Apprentice) (Krau sigil)

2 – Wizard – (Naen or Uur sigil / Naenkrau or Uurkrau power word)

3 – Wizard – (Enhanced Power Sigils)

4 – Wizard – N/A

5 – Wizard – (Extend Spell)

6 – Assassin – (Sneak Attack +1d6, Death Attack, Poison Use) (Practiced Spellcaster: Assassin)

7 – Ultimate Magus – (Arcane Spell Power +1)

8 – Ultimate Magus – (Expanded Spell Knowledge: Targeting Ray)

9 – Ultimate Magus – (Augmented Casting) (Split Ray)

10 – Ultimate Magus – (Arcane Spell Power +2, Expanded Spell Knowledge: 2nd)

11 – Ultimate Magus – (Persistent Spell)

12 – Ultimate Magus – (Expanded Spell Knowledge: 3rd) (Residual Metamagic)

13 – Ultimate Magus – (Arcane Spell Power +3)

14 – Unseen Seer – (Damage Bonus +1d6)

15 – Unseen Seer – (Advanced Learning: Hunter’s Eye) (Silent Spell, Energy Substitution:Cold)

16 – Ultimate Magus – (Expanded Spell Knowledge: Hunter’s Eye)

17 – Ultimate Magus – (Twin Spell)

18 – Ultimate Magus – (Arcane Spell Power +4, Expanded Spell Knowledge: 5th) (Quicken Spell)

19 – Assassin – (Poison Save +1, Uncanny Dodge)

20 – Assassin – (Sneak Attack +2d6)

 

This build is rather expensive to equip, as it pretty much demands a +5 Int tome and +6 items on Int, Dex, and Con, in addition to basic caster gear (bonus spell-known items don’t come cheap) and whatever stealther gear you want. However, it finishes with 156 expected HP (slightly ahead of a standard wizard and about on par with a basic rogue – but note that this is without casting things like False Life or DR spells), a base attack of +11 (typically using Ranged Touch effects at +16, before factoring in Targeting Ray or similar), saves of +10/+12/+14, and a respectable number of skill points (around 100 or so not counting prerequisites; thankfully just about every skill you’d want except Concentration is a prerequisite for something). You have the full suite of Ultimate Magus class features as well (in particular, Augmented Casting, the absolute key to this build) and the assassin’s signature Death Attack. The Death Attack DC is 25, on par with a Rogue 10 / Assassin 10 with 14 starting Int and a +6 Intelligence item, a good baseline for comparison. While a good assassin can easily get that DC much higher, they tend not to be able to packan entire suite of wizard buffs and debuffs (DC 22+spell level), nor – if you really want to be showy – the ability to Time Stop for enough rounds to observe your opponent without being detected or recognized as a threat. (It’s hardly the best kill move you have, given you have 9th level spells with a DC of 31, but you do have the ability to use Death Attack mid-battle if you wish.)

Magically, this build finishes off with 9th level wizard spells, 4th level assassin spells, and respective caster levels (without equipment boosts) of 24 and 21. This allows us to hit a few rather impressive breakpoints – for instance, Augmented Casting: Persistent Hunter’s Eye at CL 21 gives us +7d6 Sneak Attack, for a total of +10d6 (on par with Rogue 20 or Rogue 10 / Assassin 10). This is very impressive on multi-attack spells, particularly Telekinesis and Fire Shuriken. (Fire Shuriken is unclear – it implies you throw all the shuriken at once given its duration, but the wording is also open to the interpretation that you have to use iterative attacks to throw them, which makes the spell much worse. Use Scorching Ray if your DM uses the conservative interpretation.)

As an example, you can Twin Telekinesis + Quicken Fire Shuriken for twenty-one attacks and the potential for up to 408d6 damage with a zero-round prep time (well, you spend a couple rounds at the start of the day persisting your buffs, but the big thing here is you can unload that without any Arcane Fusion setup times or similar). You can add in Targeting Ray (+8 on your attack rolls as a wizard spell; it can be twinned and split if you want. If you cast it as an assassin spell it’s +7, but you can apply the twinning and splitting as the encounter demands it), Energy Vulnerability (combines perfectly with Energy Sub to dodge known resistances or immunities and target vulnerabilities; interesting, this also multiplies the 78d6 fire damage that Fire Shuriken deals, despite sneak attack not normally multiplying) or Persistent Sniper’s Shot (allows you to make sneak attacks up to the range of the spells – this isn’t useful for Fire Shuriken, but for Telekinesis it’s killer) to make this even deadlier.

Oh, and Augmented Casting also allows you to break the metamagic cap in the same way that Divine Metamagic does. This lets you do things like Persist Sniper’s Eye (the 4th level “ranged death attack” assassin spell in the SpC) and combine it with all of the above (it might allow a death attack out to any range with Persistent Sniper’s Shot as well, which is downright insane with a long-range damage ray).

 

 

We’ve managed to pack in essentially an entire wizard into an entire rogue (at the cost of quite a few skill points, sadly), with a few class features that tend to support the assassin in ways you wouldn’t expect. The choices made here support the “ultimate assassin” approach more than the usual god-on-the-battlefield approach of a wizard, but if you want to you can fall back to a typical combat mage role without having too much of a problem.

I’m not going to list all the amazing synergies here – the wizard list is just too long, even if you limit yourself to spells that would interest an assassin. I’ll leave this as an exercise, but suffice it to say, it’s pretty impressive.

 

A lot of your strengths come from persisting assassin buffs (and the best of those - stolen from the wizard list - are really limited in number due to Expanded Spell Knowledge), and although your CL is high, dispels are an option. It’s also costly in terms of wizard slots to keep those buffs going, and every persistent assassin spell you cast is one fewer spontaneous Split, Twin, Quicken, or similar spell you’re able to apply in battle later. (However, I hasten to point out that you can “cheat” this limit a bit by using scrolls + Residual Metamagic on certain spells.) Also, oddly for an assassin, you don’t have a lot of free skill points, and you don’t have Trapfinding. In this regard, you really are still a wizard playing at the assassin role, even though your class features really let you get in on that.

Apart from the untold flexibility of wizard spellcasting, you can still monkey with the build a bit. Dropping some of your metamagic options in favor of Spell Focus lets you pick up Archmage for the last couple of levels (Mastery of Elements is better than Energy Substitution, and Spell Power is always a desirable option). Alternatively, if you’re lightening up on metamagic, look into metamagic reduction feats to cheapen the load on your buff spells – even a -2 slot adjustment on Persistent Spell would let you use assassin slots to persist higher-level wizard spells! Class-wise, you could also fit in more Unseen Seer insead of Assassin for those last two levels; nothing says you can’t use those levels to advance your assassin casting either. (Strictly speaking this is probably better, but the assassin levels help with skills.) And finally, if you choose to focus only on buffs and forgo Death Attack, you could probably get by with just a 12-14 Intelligence and rebuild to work entirely off of Dexterity using Uurkrau, switching from an evil genius to a more classical acrobatic assassin. (I think the higher skill points are more worthwhile myself, but it is an interesting and more challenging project to try!)