After reading through the playtest materials (delayed because I couldn't get the stuff to download for days), I have to say I'm overall optimistic. It seems a little high-fantasy for my taste with hit dice and at-will attack cantrips, but I'll try to reserve judgment about some of that for now. Some of the explanations in this week's Legends and Lore column help to understand some of the playtest too.
I don't like how the ability scores are, once again, king. That is to say, everything happens based on your ability scores, but the math makes it look like starting with that 18 or 20 in your most relevant stat is going to be huge. Granted that'll make your other stats crap, but its a min-maxers paradise potentially. I've been contemplating a much flatter bonus system where an 18 is only +2, but I'm not sure that would work well yet. I love the Con modifier as minimum HP roll though. I had been contemplating something along the lines of half was the minimum roll, but basing it off Con is brilliant.
Advantage/disadvantage is, however, a pretty brilliant system. A re-roll is pretty important when you have a low bonus, so the math makes it more potent for your crap-stats instead of on your good rolls for a min-maxer. I'm not sure if that is a good or bad thing, but it potentially means min-maxing on your stats is going to be much better for some classes/skills, if you can get most of your important skills off with advantage via good descriptive roleplaying (Charisma and Intelligence?). I did notice that the prone condition still gives a -2 to attack rolls, which might be a typo since they said advantage is supposed to help eliminate some at-the-table math. I'm glad that they don't seem to have decided on the idea of using 1d4 or 1d6 for a bonus at least. Something like the thief's skill mastery might be doable with this mechanism as well. I'm also wondering what it would look like, mathematically, if the second die rolled were 1d12 instead of 1d20. You'd be more likely to "roll" a score in the 8-9 range probably, but still have the potential of catastrophic failure. Just less-so. Maybe that average roll isn't quite high enough to make a difference if you're not pretty maxed out though.
I though they were going to do more with silver pieces, so the equipment section's prices baffled me a bit.
Hit dice seem ok, but I might like a limit that one can only spend so many per short rest. For extended rests, it'd be interesting if one only recovered hit dice and not any HP perhaps. I'm still a little uncertain. Also the once/level thing seems a bit... low? Or low at first and high later on maybe.
I'm also a little unsure of some of the scaling math. The rogue seems to gain a die of sneak attack at every level, which is pretty potent. I'll have to reserve judgment till we can see more than a 3-level playtest. Same as the class features, really. This playtest is about the basic mechanics.
I feel similar about themes. They seem... silly maybe. But if they're just granting feats, its just extra wording on my sheet. I don't mind if a fighter could take a feat and gain some minor spellcasting powers, that's pretty cool. But how that fits in with multiclassing and what annoying pages of fluff are going to be given to these feat-delivery packages remains to be seen. The backgrounds are nice, but I still think some classes or races should have innate skills as well.
Overall, I like the magic system except for the "minor" spells (cantrips/orisons). For example, I like how the grease spell states a bunch of different possible uses and its possible effects. The attack minor spells though seem... lackluster. They're generally a replacement for a weapon, and do damage just like a weapon. Ray of Frost might be a much more interesting spell if it did one thing, though I suppose it should since I could easily do this with the rules. So, one effect when targeting the ground (creating a slippery surface), another when targeting a small fire (extinguishing it), another when aimed at the target's eyes, etc. Maybe that's too much for one spell, but as a player I'd expect to potentially be able to do this. That makes the at-will spells really potent potentially. If the cantrips were once per encounter, I wouldn't mind this level of flexibility. If they're really at-will though, I think they should potentially do much less. Maybe the class or theme would let one cantrip be mastered completely, while the others are just per encounter? But really, the shocking grasp can no longer be used when attacking with metal weapons? Wizards can take Magic Missile to always be able to damage an enemy with no attack roll every turn? And eventually it grows stronger so you can make multiple attacks with it? Radiant Lance gives any cleric a "magic" crossbow? Meh. A bit too high-fantasy in my book, so hopefully the 'tone it down' options won't devastate the casting classes. Or maybe there'll just be alternative magician and votary classes?
A quick list of positives: Ritually casting spells, a reasonable movement system, skills in general, simplified turn mechanics, and hazards on skill checks. Also, just about everything else, really.
I don't like how the ability scores are, once again, king. That is to say, everything happens based on your ability scores, but the math makes it look like starting with that 18 or 20 in your most relevant stat is going to be huge. Granted that'll make your other stats crap, but its a min-maxers paradise potentially. I've been contemplating a much flatter bonus system where an 18 is only +2, but I'm not sure that would work well yet. I love the Con modifier as minimum HP roll though. I had been contemplating something along the lines of half was the minimum roll, but basing it off Con is brilliant.
Advantage/disadvantage is, however, a pretty brilliant system. A re-roll is pretty important when you have a low bonus, so the math makes it more potent for your crap-stats instead of on your good rolls for a min-maxer. I'm not sure if that is a good or bad thing, but it potentially means min-maxing on your stats is going to be much better for some classes/skills, if you can get most of your important skills off with advantage via good descriptive roleplaying (Charisma and Intelligence?). I did notice that the prone condition still gives a -2 to attack rolls, which might be a typo since they said advantage is supposed to help eliminate some at-the-table math. I'm glad that they don't seem to have decided on the idea of using 1d4 or 1d6 for a bonus at least. Something like the thief's skill mastery might be doable with this mechanism as well. I'm also wondering what it would look like, mathematically, if the second die rolled were 1d12 instead of 1d20. You'd be more likely to "roll" a score in the 8-9 range probably, but still have the potential of catastrophic failure. Just less-so. Maybe that average roll isn't quite high enough to make a difference if you're not pretty maxed out though.
I though they were going to do more with silver pieces, so the equipment section's prices baffled me a bit.
Hit dice seem ok, but I might like a limit that one can only spend so many per short rest. For extended rests, it'd be interesting if one only recovered hit dice and not any HP perhaps. I'm still a little uncertain. Also the once/level thing seems a bit... low? Or low at first and high later on maybe.
I'm also a little unsure of some of the scaling math. The rogue seems to gain a die of sneak attack at every level, which is pretty potent. I'll have to reserve judgment till we can see more than a 3-level playtest. Same as the class features, really. This playtest is about the basic mechanics.
I feel similar about themes. They seem... silly maybe. But if they're just granting feats, its just extra wording on my sheet. I don't mind if a fighter could take a feat and gain some minor spellcasting powers, that's pretty cool. But how that fits in with multiclassing and what annoying pages of fluff are going to be given to these feat-delivery packages remains to be seen. The backgrounds are nice, but I still think some classes or races should have innate skills as well.
Overall, I like the magic system except for the "minor" spells (cantrips/orisons). For example, I like how the grease spell states a bunch of different possible uses and its possible effects. The attack minor spells though seem... lackluster. They're generally a replacement for a weapon, and do damage just like a weapon. Ray of Frost might be a much more interesting spell if it did one thing, though I suppose it should since I could easily do this with the rules. So, one effect when targeting the ground (creating a slippery surface), another when targeting a small fire (extinguishing it), another when aimed at the target's eyes, etc. Maybe that's too much for one spell, but as a player I'd expect to potentially be able to do this. That makes the at-will spells really potent potentially. If the cantrips were once per encounter, I wouldn't mind this level of flexibility. If they're really at-will though, I think they should potentially do much less. Maybe the class or theme would let one cantrip be mastered completely, while the others are just per encounter? But really, the shocking grasp can no longer be used when attacking with metal weapons? Wizards can take Magic Missile to always be able to damage an enemy with no attack roll every turn? And eventually it grows stronger so you can make multiple attacks with it? Radiant Lance gives any cleric a "magic" crossbow? Meh. A bit too high-fantasy in my book, so hopefully the 'tone it down' options won't devastate the casting classes. Or maybe there'll just be alternative magician and votary classes?
A quick list of positives: Ritually casting spells, a reasonable movement system, skills in general, simplified turn mechanics, and hazards on skill checks. Also, just about everything else, really.