I made some changes to the master plan.
CONSTRUCT PASSIVE ABILITY:50% Construct works 100%
10% Construct overheats and does not attack during next turn.
10% Construct malfunctions and cannot use its ability during next turn.
10% Construct gets confused and will attack its owner during next turn.
10% Construct runs out of battery and must be recharged (card goes back to your hand).
10% Construct suffers a serious malfunction and takes 10 damage.
First of all, I think that there should be a 50% chance of something bad happening because I like the 50/50 thing. I think that there should be 4-5 possible bad things, each with the same chance of happening. I chose 5 and 10% for now.
I tried to make the effects as simple as possible. I changed the "switch sides" to "attacks owner". I changed the destruction thing to taking damage. The amount of damage taken will probably match with the HP that the Constructs will have. This way it will destroy the Construct IF you have not buffed it.
I also don't like the sole destruction mechanic, so I came up with this: 'Construct is destroyed and generates Scraps.' Scraps could be a permanent that is useless, or does something minor.
I like the scraps thing a lot. It would open some very interesting possibilities BUT I think it would also make things way too complex. This whole construct thing is already complicated, and adding Scrap mechanic, might take it over the edge.
As for the Repair Droid, I had this idea: 'Repair: Lower the chance for Constructs to become defective each turn. Turn all Scraps into a random Construct.' The chance for all defects would be lowered by 1%, and the chance for no defect would then be raised by 5%.
Here's the first draft of Repair Droids that I made.
Repair Droids. Special cards whose only purpose is to repair broken down Constructs.
This "Lower the chance for Constructs to become defective each turn" could me a mechanic that upped Repair Droids did (rename it to Improvement Droids), but I fear it could once again make things too complex. I don't think there should be any nerfed Constructive passive abilities. Only way it could work is if those Droids removed the passive ability altogether. But even that, like I said, would probably make things too complex, I don't know..
I agree that a random effect could be intresting. How about the following:
Construct / Fixer
At the start of each turn, every creature is checked for the active "Fixer". A variable stores the number of creatures with "Fixer" in play.
At the start of each turn, every creature is checked for the passive "Construct": if the creature is a construct then a random number between 00 and 99 is generated, plus another number for every "Fixer" in play. The highest number is kept. Then, this sound effect is played (http://www.pacdv.com/sounds/mechanical_sound_effects/spring_3.wav) (it's free to use) and an effect is cast upon the construct, depending on the number:
00 - 04: the construct stops working an falls into pieces. It is destroyed.
05 - 09: the construct's systems stop working. It is lobotomized.
10 - 19: the construct's battery runs dry: it is frozen for 3 turns (frozen creatures' passives do not work, so there won't be any additional damage).
20 - 34: the construct's power core has a short circuit. It takes 5 damages.
35 - 49: the construct overheats. It takes 3 damages.
50 - 89: nothing happens.
90 - 94: the construct repairs itself. He is healed by 5 hp.
95 - 99: the construct regains part of its lost efficiency. It gains a variable +1/+5 to both attack and hp.
This system is re-using parts of the game to reproduce effects in as clean and simple a way as possible. Also, I think the "Fixer" thing is pretty nice and balanced this way.
EDIT: some notes on balancing. Constructs should have (also thematically) high hps, somewhere between 6 and 10. That way there is a pretty small chance that they will die after only one attack, but it will be pretty sure they won't stick around for more than 7-8 attacks without help. Which is plenty in the current metagame. I therefore think the passive is worth a -1 cost reduction, and no more than that.
I don't know.. it definitely makes sense, but once again, it's pretty complex imo. Too many effects and percentages change too much for my liking. But I'll have to think about it some more.
The sound effect thing is a pretty cool touch. I'll have to remember to add sound effects for flavor to each card topic when I start posting them.