While rustler is very vulnerable to cc, it is also very powerful in decks that use it, so I think it's fine.
However Leaf Dragon seems a little lacking to me. This is because one of the main decks that uses leaf dragons (Firefly queen) can't use it anymore when upgraded, due to fireflies producing fire quanta instead of light quanta. In this tread showing decks that use rustler/leaf dragon, they all use rustlers, and most use fireflies. It looks to me like many of them would be destroyed when all cards are upgraded (or rather rustler/leaf dragon would be removed for better options).
So, in interest of leaf dragon remaining reliant when upgraded, I think it should be able to convert either
or
quanta into
(randomly chosen). This allows FFQ decks to use it in the same capacity upped as unupped, while retaining the ability for any old decks that used it to use it without it being any weaker or more powerful then before.
If this is impossible, I would say 1 of any element converted into
, but then you run into the problem of
->
infinitely, so that would have to be prevented somehow. (max times it can be cast? Ability can't be activated if you only have life quanta?)
A third way it could be buffed is simply reducing the cost of the creature to 0. This would make it much easier to include in decks since you don't have to worry about getting the first
you need in order to start your
generation.
Alternatively, a buff to this card would be if upgraded fireflies gave
instead of
.
