Well, a set numerical deduction doesn't make sense either. I much prefer a percentage.
Also, if you followed my logic there, then this part should also make sense.
The deduction doesn't need to be based on the number of effects, but rather the number of types of effects.
All healing can be one. All summoning can be one (I know different creatures have different utility, but that, all things considered, is minor right now). All drawing can be one.
The reason for breaking based on classes of effect and not just number of effects is that, if one healing will be useful, so will another, so they don't need to both subtract. [If you were doing a super detailed analysis (as I do in my classes. I study game theory.) you would have to make a distinction between different amounts of healing, because healing 20 is less useful if you are at 90.... but that is not necessary right now]
Sorry. That is getting away from the point. This point is that, unless both effects are always useful, there should be a cost that is mildly less than just the average cost. What that deduction is, can't be done by a simple calculation.
your logic makes sense actually, so should 2-4 random effects be -1 cost, 5-7 be -2, and 8+ be -3, does that seem fair?
i think that set percentages should also be a factor in determining cost, like this card
I would say that, although mathematically, it won't always work, most of the time, that will be fair. Would you mind showing OldTrees this post? Maybe this may finally convince him.