CardName: Tideshaper
Cost: U
Type: Creature - Merfolk Wizard
Pow/Tgh: 1/1
Rules Text: {T}: Landscape target land. (Until end of turn, that becomes
a basic land type that could produce mana of one of this
cards colors.)
Flavour Text: She molds water like the sculptor molds clay, creating works
of equal, if not greater, value.
Set/Rarity: Zaethereria Common
Tideshaper
C
Creature – Merfolk Wizard
: Landscape target land. (Until end of turn, that becomes a basic land type that could produce mana of one of this cards colors.)
She molds water like the sculptor molds clay, creating works of equal, if not greater, value.
I'll note in passing that, while Dream Thrush and Reef Shaman could do this, that proved rather too effective at denying the opponents mana of the colours they want in Limited. More recent takes on the same idea have one restriction or another that stops it being used in that way: Grixis Illusionist only hits your lands, while Tideshaper Mystic could only be used during your turn (so it only shuts off instants, not creatures or sorceries). Streambed Aquitects could still make things into Islands on the opponent's turn, but it had incentives not to - you were passing up the chance to make one of your attackers bigger or making them unblockable, and also passing up the chance to block with it as a 3/4; not to mention costing rather than just .
: Landscape target land. (Until end of turn, that becomes a basic land type that could produce mana of one of this cards colors.)
I'll note in passing that, while Dream Thrush and Reef Shaman could do this, that proved rather too effective at denying the opponents mana of the colours they want in Limited. More recent takes on the same idea have one restriction or another that stops it being used in that way: Grixis Illusionist only hits your lands, while Tideshaper Mystic could only be used during your turn (so it only shuts off instants, not creatures or sorceries). Streambed Aquitects could still make things into Islands on the opponent's turn, but it had incentives not to - you were passing up the chance to make one of your attackers bigger or making them unblockable, and also passing up the chance to block with it as a 3/4; not to mention costing
rather than just 
.