Here are my revised thoughts on making sure you can mono in a tree if you so desire. This will most likely be brushed aside, since it seems we are going in a different direction, but I wanted to get my ideas here for discussion.
Update the level cap to 25 (nice round number)
Make it so you can't get 2 master talents (too imbalanced if you get the 'right' combination)
Update the trees slightly to what I have shown below.
It takes 13 points to get to mastery of a tree. This will allow "most" builds unable to gain 2 masteries organically. Only problem is the scholar talent, and if you state you can't get 2 master talents, we're good. The T1, T2, T3, M (master) talents are as we have them now. The P is a new talent for each tree called "Potency against **. It gives you a bonus for beating your opposite, like "Bane of **" does now. My thought is "increase their discard by 2, your salvage by 2 on a win". Many other options available. This added talent is to both increase the 'feel' of the "bane of **" skill within the tree (seems like a loner and needs a friend) and also to make 2 master builds not work 'normally'.
The star talents above would be for people who become a master of the element. Each will have 6 levels, we can have them improve one branch of the tree. As you can tell, if you mono, you take 13 points to become the master and have 12 points left. There are 18 points needed to fill up these extras. This way there are choices for each mono and no two builds should be the same. You can go 6 in two talents or a combination. You can lock people out of these extras if they go into another tree, or let them have them still for becoming a master of the element. Adds a feeling of being better than everyone else at what you do.
For examples, I'll take the life tree, since I know that one best.
The shaman side master talents could be:
- Cooldown of Breath of Life is now 5 days
- You can use 8 upgraded cards if you battle on a forest hex
- Nature rituals now costs only 1 action point but only usable twice per day
- You can use 4 elite cockatrice during any battle, they disappear after duel ends.
- Cooldown of Breath of Life is now 4 days and doesn't cost a relic.
- If you use animal form, you can charge for free this round.
For Predator they could be:
- Scouting is now free but only usable once a day.
- Setting a lotus trap is now free but only usable once a day.
- When you breed 2 of the same creatures, you get a third for free.
- Pack hunter's bonus for you is now 3 upgraded cards per ally.
- If you EM your opponent in any duel, you do not die if you lose
- You may now have 2 lotus traps active at any time.
For the center talents, they could be the same for each element, focused on killing your opposite.
- Gain 4xp for beating a *** in battle
- When facing a wanted *** elementalist you gain 6 upgrades.
- Your opponents cannot use a *** mark against you. (Unless they have no other option)
- Your aggressive charge against a *** elementalist moves you three spaces towards them.
- Your siege against *** towns is twice as effective.
- You may name one *** card before a duel, your opponent may not use that card.
It might be a daunting effort to create unique and wanted abilities for all of the trees, so this might be too big of an effort, but since we are assuming they only go to masters of each element and if we make them only for mono people, they can be strong so that they are attractive. We are also only increasing the strength of already earned abilities, like upgrading a card increases its effectiveness, so finding ways to make them work shouldn't be too mind-wrenching.