1.) Infiltrate can be done even while fighting (Pick Lock (and advanced) cannot) "Oh crap! I don't have the key to unlock this door (or chest), and this stupid aggo mob doesn't ever track away from that room!"
infiltrate door (or chest)/bird mob/flee

2.) Infiltrate is INT based, rather than Dex based, so if you're a gnome or elf, Infiltrate has a (slightly) higher chance of success (This is essentially (almost) a moot point, though, since a high quality pick makes up for the difference, and 100% skill + max dex guarantees success IF the lock is pickable according to your advanced training status. Of course, if you're playing a duergar, felar, or svirf thief, Infiltrate is probably not going to be as good as a physical pick.)

3.) If I recall correctly, Infiltrate has 1 round longer lag.

4.) Infiltrate requires no physical pick.

5.) Infiltrate DOES work on locks that require Advanced Picklock, but ONLY if you ALSO have Advanced Picklock (i.e. if Pick Lock + Advanced Lockpick will open the lock, then Infiltrate + Advanced Picklock will also open it).

When it comes to the Locksmith skill, you cannot create a makeshift key for an advanced lock, but you CAN create a copy of an existing key for an advanced lock. When making a copy of a key that crumbles, the copy will also crumble, but its crumble timer is longer than the original, which usually means less need to go get the original again multiple times.*

When making a copy of a key for any lock, if the original does not crumble, then the copy will also not crumble.


*True as of the last time I played a thief with the Locksmith skill, which was, admittedly, a few years ago at least.

I could be mistaken on this next comment, but I think the crumbliness of the copied key is also (at least partially) based on how successful you were in the skill check. In other words, higher skill % in Locksmith results in greater likelihood the key doesn't crumble. The last time I played a Locksmith thief, which was post-nerf, I recall talking to another locksmith thief who was active at the time, and being told that copying the Seantryn Empress's key results in a copy that crumbles just as fast as the orginal, making locksmith useless in that instance. Later, when I was able to test it out, I recall making one copy that crumbled, and then later making one that didn't. Now, as mentioned above, that was several years ago, which was very shortly post-nerfing. I don't know if that was a bug which has since been fixed, or if that was a design that was overlooked by players. I just know what I experienced at that time, and I haven't bothered to revisit that build since. I also didn't keep that character around very long due to RL interference.

Advanced Picklock still has a great many uses, and I still regularly take it with most of my thief builds. There are only a few build types in which I forgo Advanced Picklock.

The main locks that have been upgraded to resist Advanced Picklock are locks in the most difficult and dangerous of places. Specifically, all the chests in the ancient dragon lairs. Those all got nerfed about a day or two after I picked Tiamat's chest and plundered it for every item it had the potential to contain (i.e. there was nothing missing before I looted it). Also to get nerfed, though much later, was the trapdoor to Defiance, probably based on the exact same logic as the nerfing of the ancient dragon chests. Seantryn Empress chest was NEVER pickable with Advanced Picklock. That one always required a key, even if the key was a copy of the original. There may be a few other locks that have been fortified against Advanced Picklock that I've forgotten or didn't know about that USED to be pickable, but I can't think of them at the moment.

Also, when it comes to making a tanky thief, Lore of the Ages should not be ignored. When I played Tellick, I went on a hell trip and out-tanked the Nexus felar spear spec who had Dance Upon the Southern Winds and Ward of Blades for his legacy. I was using Shield Block (felar had spin), a sword, 100% dodge, 75% Lore of Ages, and had 25 dex (passed off my heavy chest to someone else in the party to carry while I tanked). The mob I was fighting had a (Famous) polearm that did shocking bite damage. To deal with the lightning damage, I had a resist lighting item (in the days when a resist item replaced vuln with full resist), so my lightning resist was equal to the felar with aegis lightning from our healer. All other protections were equal between us. The felar warrior had a superior weapon for parrying, and Spin instead of Shield block (Spin is also superior to Shield Block if I'm not mistaken), plus nearly twice my HP for being a warrior with much higher CON. Felar also had proficiency in polearm, and I didn't. And yet, Lore of the Ages trumped all his advantages. The felar was only able to hang in there between 5 to 10 rounds before he had to fall back, as he was taking damage faster than the healer could heal him. I only stepped up to try as a means of keeping the mob busy for a few rounds while the felar was in healing sleep. I ended up holding off the mob without having to flee for several ticks beyond the duration of the healing sleep. Healer had absolutely no trouble keeping up with healing me, and even had time to healing sleep himself while I held the line without healing. By the end of the fight, my Lore of the Ages skill was 100% It also allows you to avoid hostile progs from magical weapons as well, which can be a MAJOR lifesaver (or gear saver) when you come across them. Also good for avoiding elemental controls from AP unholy weapons.

So in short, if you want a tanky thief, and you're already considering the Mystic path, Lore of the Ages really adds A LOT of defense vs weapons of (Famous) rarity and beyond (I think (Infamous) counts too. Not really sure on the distinctions between (Famous) and (Infamous)).