I just wanted to give some real practical tips on how to use the wabi-sabi technique when designing game effects. Say you're making a deck of event cards or special powers that apply to different points in the game. There are two things happening here.
Power: This is how much of an impact the instance has on a subject. In your case, the "instance" might be an Event Card, or a Faction Power, or a Magic Item. If your instance nudges the game, that's Weak. If your instance smashes the game, that's Strong.
Rarity: This is the subject affected by the instance. The "subject" might be the players, a resource pool, or some other in-game construct. We already covered this in the last post, specifically in regards to card games. If the subject is present in the game very often, you can say it is Common. If it come sup rarely, you can say it is Rare.
Card games are an easy format to control rarity, since you can divide up the deck into suits, ranks, or whatever level of specificity you like. For example, if you have some minor point bonuses, modest bonuses and strong bonuses, you can design those bonuses knowing how likely they are to come up. So, your minor bonus could apply to 2/3 of the deck. The modest bonus may apply only to 1/4 of the deck. The strong bonus may only apply to 1/6 of the deck.
Controlling rarity in other formats is a bit more difficult and can sometimes take some math. For example, with Mark Sherry's help, we calculated that the average game of Do: Pilgrims of the Flying Temple would last around 14 turns, based on a few variables like the size of the group. With that knowledge, I could impose goal structures that we knew would be easier or more difficult to accomplish within that amount of time. If I introduced a power that made accomplishing those goals easier, I knew exactly how powerful it could be and whether it would break the game.
How can you use this knowledge? Well, in a card game, you can easily design powers using simple game terms. "All owners of a Courage or Power card gets 1 victory point." This is balanced because the subject is common, but the instance is weak. Or "If you have three Fire cards, you get 5 victory points." This is balanced because the subject is a little rare, but not hard to achieve, and the instance is strong enough to make it worth the trouble. Or "All owners of a Fire card and Eagle card get 10 victory points." This is balanced because the subject is very rare, but the instance is strong enough to be a tempting tactic.
The key in all this is knowing the structure of your game, whether it's a deck, or turn order, or the number of players. You'll feel confident designing big bonuses because you know how likely they are to apply. Playtesting is still important, but at least you have a bit more control in the early design phase.