My thesis is compost should increase the amount of damage the bramble sheild can absorb. This is due to the fact that a qot wastes many skill points on useless skills late in the game and she desperatly needs a useful ability late game.
Most people who play queen of thorns just place points in shield and her 2 aoe attacks. This means you have to wait a few levels then drop 2-3 skill points. This is very effective early mid game.
However, once level 10 hits there is nothing to look forward to till lvl 15 (where you drop 2 skills). After lvl 15 there is NOTHING that can possibly help you. Shamblers are useless after around lvl 7, plus there are 4 different skills on can get to increase their value (which is still next to nothing). One could possibly just use shamblers as health potions using mulch...but its a very expensive potion mana wise. Keeping up queens sheid and aoe attacks will suck most of your mana. Shamblers are a waste if you go aoe queen.
The other option is to get uproot. A few points in this might be somewhat usefull....the only problem is by lvl 10-15 most towers are dropping instantly....so this skill does nothing for you.
Compost is a skill which helps the useless abilities i just mentioned. So basically, if you are queen of thorns, and you wish to win, you better fo it by lvl 15, otherwise enemy will just get more powerful while you sit and smell your own farts. Most games only last till lvl12, but on crucible the game can last a mightly long time. Having 8 wasted skill points is a mighty big shame.
My solution: have compost increase the amount of damage the sheild can take. Sheild is a wonderful ability early game, but it is shit late game. If compost upped amount of damage it takes, then late game the sheild would have more power. This would also not make sheild too strong early game since not many players could afford to drop points in it till lvl 10.