CardName: Conquered Treeline
Cost:
Type: Land
Pow/Tgh: /
Rules Text: {T}: Add {1} to your mana pool.
When a creature you control deals damage to an opponent, you
may sacrifice Conquered Treeline, search your library for a
forest or a mountain card, and put it onto the battlefield.
Flavour Text:
Set/Rarity: Multiverse Design Challenge None
Conquered Treeline
Land
: Add to your mana pool.
When a creature you control deals damage to an opponent, you may sacrifice Conquered Treeline, search your library for a forest or a mountain card, and put it onto the battlefield.
This stretches "not a mana ability" but it technically isn't. I thought of it by asking, what triggered abilities a land could have.
I'm not sure if this is too strong or too weak or too swingy: it's a fetchland that's a lot better than a fetchland if everything happens just right, but can easily leave you stranded on colourless mana.
I envisaged a cycle, probably (but not absolutely sure) with the same trigger for different pairs of basic land types.
: Add 
to your mana pool.
See Challenge # 110.
This stretches "not a mana ability" but it technically isn't. I thought of it by asking, what triggered abilities a land could have.
I'm not sure if this is too strong or too weak or too swingy: it's a fetchland that's a lot better than a fetchland if everything happens just right, but can easily leave you stranded on colourless mana.
I envisaged a cycle, probably (but not absolutely sure) with the same trigger for different pairs of basic land types.