I just looked at the Leaderboards of people who are playing the Monk in Seasonal. Every single leader is using Taeguk, which gives you a tiny damage increase that will stack up to ten times. Since these players are doing better than me, I must be missing something. Why is Taeguk considered a valuable gem?
it’s a channeling skill gem, provides good damage + armor
The “downside” of Teaguk is that the damage is low, however in a channeling build it is consistent and noteworthy which why it is used in most any channeling build. Before being “locked” to channeling skills it was also used quite frequently for other skills.
It is also the only gem to offer both damage and damage reduction (although only 5-10%) but it still matters.
I wouldn’t call the damage low. For example at rank 100 full 10 stacks provide 60% increased damage. The actual downside is that the damage is additive, not multiplicative as some other gems.
Exactly that, which makes it weaker in some builds rather than others. The less DiBS you stack the stronger it is, and most builds that do use channeling tends to use a lot of DiBS to increase damage output, as there’s not a lot of multiplicative sources.