artificer: I'd love to see this piece get some sort of enhancement.
Someone else mentioned maybe they could stun at a limited distance.
maybe they could alternatively limit motion? slow down a player (entrap?) so they move one less space per turn for a turn?
casting range of like 4?
perhaps they should also be able to "de-mechanize", turn an inorganic unit back to organic. (not buildings of course)
and against an inorganic unit, they should have some power to either destroy completely (disassemble power?)
or massively weaken. within a short range though, maybe two? so they could take out golems, or siege units, or any other clockworks. i would say destroy at range 2 (similar power to a summoner that can capture at range 2, that seems to work well for that piece). if they could only weaken an inorganic, maybe remove shields, or decrease life? perhaps range 4 would work well.
another alternative, maybe the artificer could lay mines? might be an interesting addition.
last alternative. they could almost be like an inorganic priest unit. (they already act as an inorganic "healer") so why not instead of destroy (disassemble power) they could take control of an enemy inorganic unit? since its best if this unit only has one action, the take control would have to have some range, perhaps 4. but it could be limited in how many it could control at once. i would say one, maybe two units.
wyvern: this is another piece that just doesn't seem to live up to its potential.
i agree with others that have mentioned, egg hatching should be shortened to 2 turns.
but perhaps total egg production should be limited over the course of a game? (maybe 5 eggs per wyvern?)
against the AI, the unlimited attack upon approach is fantastic, but against players, this seems too overpowered. perhaps this should be limited to neighborhood of 2-4 attacks? (this is, if the egg hatching time were reduced).
another option is keep the unlimited attack, but perhaps this should be distance of only 1 space. not sure the rationale that this creature can get you at two spaces away. (again, i would only do this if the egg hatching time is reduced)
if space of counter attack is reduced, i might add one more power to this beastie as a balance.
if power remains the same, i might suggest giving it two attacks, instead of the one.
another option with this critter, although this would be a lot more programming work, would be neat if it could build a nest. so all eggs have to be laid there. wyvern has to go feed, but once it feeds, it can choose where to build its nest. nest then would work like a barracks. but maybe these should be wyverlings? not able to reproduce themselves, but capable of eating and attacking like the parent. maybe 2 less life. production would be two wyverlings per "clutch". so upon first feeding, and making the nest, it could produce two wyverlings, over the next two turns. you could then be limited to total of two wyverlings per time. if one gets killed, you would need to have the main wyvern feed again, and return to nest, to recharge egg production.
i know this sounds like a lot of overhead, but it could be really interesting, and it makes it sort of more like a real bird (or dragon-like thing) might do this.