An Assassin is great at high levels, UAI & Assassination are fantastic as are epic traps.
If you dual class to a fighter you can gain GM & further atks per round, once you reach epic level you'll gain feats such as Whirlwind, Hardness & Critcal Strike.
The issue is as many others have already mentioned - that Assassins gain the highest bonuses from reaching level 21(backstab, poison, traps), which makes dualing very difficult - you'll have to wait a long period of time to regain your Assassin abilities. Or change your play-style so it's more focused on gaining rapid XP & still wait a fairly long time.
So with all things BG read over everything that's been put foward & make your own choice about how you'd like to play, you can always do another playthrough & try it the other way.
If GM is what you want on an assassin, the easiest thing would be fighter, dc to thief at 3, then shadowkeep the kit on. You'd actually GM in BG1. That's cheating though . However, an early dual to thief isn't a bad move if you just want GM, though it would cap your backstab at x5.
The thing is, by the time one gets to x6-x7 backstab, I have to wonder if there is much practical difference between Assassin and pure thief, in terms of one-shotting baddies. I'd wager that once HLAs are unlocked, there is no practical difference, but in that late SoA time the assassin's extra backstab damage probably makes a difference. The assassinate+x5 BS wil OHKO most baddies (that can be backstabbed) after 3m xp.
Even dualing from fighter 2 to thief will unlock the ability to GM a weapon. I'd probably dual at 7, 6, or 3 with BG1 in mind. At three, you get an additional prof, which will let you hit GM at thief 8, and x3 backstab at thief 9. Ditto for 6, plus a small bonus to thac0 and hp over a three-dual. 7 nets you an extra half-attack, which will be useful throughout the saga, but delays your x3backstab till SoA, unless you remove the cap (you'll hit the cap at thief 8).
If you don't want to cheat, I'd recommend taking berserker or kensai as the starting kit. The Kensai/thief is unbelievable once you get UAI, but it is a long wait for a huge payoff. Unless you're super-experienced, I'd go berserker->thief. The ability to become immune to some of the most debilitating status effects (and game-enders) in the game is awesome. Pretty much the only weakness is petrification, and you'll love the protection from Maze and Imprisonment in SoA/ToB.
I know it's a bit off-topic, but I'd thought I'd give you an alternative if what you wanted is grandmastery backstabs.
Comments
If you dual class to a fighter you can gain GM & further atks per round, once you reach epic level you'll gain feats such as Whirlwind, Hardness & Critcal Strike.
The issue is as many others have already mentioned - that Assassins gain the highest bonuses from reaching level 21(backstab, poison, traps), which makes dualing very difficult - you'll have to wait a long period of time to regain your Assassin abilities. Or change your play-style so it's more focused on gaining rapid XP & still wait a fairly long time.
So with all things BG read over everything that's been put foward & make your own choice about how you'd like to play, you can always do another playthrough & try it the other way.
I wont even get to run through BG2 by then :O
cruel fate
The thing is, by the time one gets to x6-x7 backstab, I have to wonder if there is much practical difference between Assassin and pure thief, in terms of one-shotting baddies. I'd wager that once HLAs are unlocked, there is no practical difference, but in that late SoA time the assassin's extra backstab damage probably makes a difference. The assassinate+x5 BS wil OHKO most baddies (that can be backstabbed) after 3m xp.
Even dualing from fighter 2 to thief will unlock the ability to GM a weapon. I'd probably dual at 7, 6, or 3 with BG1 in mind. At three, you get an additional prof, which will let you hit GM at thief 8, and x3 backstab at thief 9. Ditto for 6, plus a small bonus to thac0 and hp over a three-dual. 7 nets you an extra half-attack, which will be useful throughout the saga, but delays your x3backstab till SoA, unless you remove the cap (you'll hit the cap at thief 8).
If you don't want to cheat, I'd recommend taking berserker or kensai as the starting kit. The Kensai/thief is unbelievable once you get UAI, but it is a long wait for a huge payoff. Unless you're super-experienced, I'd go berserker->thief. The ability to become immune to some of the most debilitating status effects (and game-enders) in the game is awesome. Pretty much the only weakness is petrification, and you'll love the protection from Maze and Imprisonment in SoA/ToB.
I know it's a bit off-topic, but I'd thought I'd give you an alternative if what you wanted is grandmastery backstabs.