I'm not sure how to word this but I think a land like this could be useful and balanced in type 1. I also have no name for it.
Legendary Land
Lose four life when ''this 'comes into play.
"This" comes into play tapped.
Sacrifice this - Destroy target permanent.
t: add one colorless mana to your mana pool
edited for some clarity.
I think what you ment to do (and correct me if i'm wrong)
Toxic Waste Dump
Legendary Land
Toxic Waste Dump comes into play tapped
when toxic waste dump comes into play lose 4 life
Tap: Sacrifice Toxic Waste Dump destory target permanent
Tap: Add 1 Colorless mana to your mana pool
The only difference is the "Tap: Sacrifice" instead of just "sacrifice" therefor making the comes into play tapped a little more important (which I thought you ment) Maybe not though interesting card, very powerful (also with the legandary status if you do have to tap to destroy you can "negate" it with putting your own card into play (with the new legends rule) )