Here's a video showing Undeen's Taunt in action. It seems I was actually wrong - it's not that her Taunt doesn't work against Water minions, it might actually be that it only works for 1 turn, unlike with other Taunt users where it works indefinitely.
I'll keep an eye on Elf Archer, 'cause I can't help but think his/her "double damage" effect would be more appropriate on a weaker minion, especially considering Elf Archer's power can be boosted by not only Scholar Angel, but also Elf Commander.
My opinion on poison: Your "Poison to all" effect is a good idea for what poison should be in general. Not instant death like Deathtouch but capable of taking out multiple minions over time. I look forward to seeing that in action, though it'd still need to start off doing 1 damage, then stacking more damage with additional poison effects.
I mistook what "Sort By Value" meant. I figured it'd sort the collection in order of mana cost. So all the 0 cost, then 1 cost, 2 cost, etc.
Thanks for getting back to me. I look forward to seeing what you end up coming up with.