Onderzeeboot
Ecstatic Orb
Why not turn that idea around and print something like:I'm kind of thinking 5 random effects, not mana fixing. Fetchable spell-lands are hard to balance, though
White Spellfetch
Land
At the beginning of your upkeep, return target creature with converted casting cost 1 from your graveyard to the battlefield.
T, pay 1 life, sac White Spellfetch: Search your library for a plains card and put it onto the battlefield. Then shuffle your library.
Blue Spellfetch
Land
At the beginning of your upkeep, draw a card, then discard a card.
T, pay 1 life, sac Blue Spellfetch: Search your library for an island card and put it onto the battlefield. Then shuffle your library.
Black Spellfetch
Land
At the beginning of your upkeep, each opponent loses 1 life and you gain 1 life.
T, pay 1 life, sac Black Spellfetch: Search your library for a swamp card and put it onto the battlefield. Then shuffle your library.
Red Spellfetch
Land
At the beginning of your upkeep, each player sacrifices a land.
T, pay 1 life, sac Red Spellfetch: Search your library for a mountain card and put it onto the battlefield. Then shuffle your library.
Green Spellfetch
Land
At the beginning of your upkeep, put a +1/+1 counter on target creature.
T, pay 1 life, sac Green Spellfetch: Search your library for a forest card and put it onto the battlefield. Then shuffle your library.
Obviously a bit pushed, but by putting the effect on a fetch you have to chose between the spell effect and the mana.
You could also tweak them to search for basic lands only if you want to further limit the fixing capabilities of Therese.