­High Tide

Blue mana bump. Yeah. Howabout no. But on the flipside, this is one of the few FE cards that actually stands the test of time. Because it's horribly abusable to make infinite mana.

Which isn't really a GOOD reason to preserve as is.

The card is instant, suggetsing it's use is "You think I only have {some} land untapped and that's not enough to do anything; but hah! I have more!"

Except, um, this uses one blue, and you have a second island up (or it is useless) so you already had at least up? So you could already cast Counterspell so how is this a useful surprise? (I mean, ok, sometimes it is. Spell Blast is a thing...)

So mainly it gets used in your turn as "Ok, have 2(n-1) mana this turn". Which is, well, it's still pretty useful. But not really a blue thing to do.

Well, blue DOES get to modify lands... (maybe 'ueot all your lands are islands'?) but it certainly gets to modify spells. And I think just a slight variation, and ensuring it exiles to prevent ridiculous recursion, is probably the fix I want.

Does this NEED to be an instant? Is it too confusing as one? It has value at instant, but as discussed; not a huge amount. Make sorcery for simplification.

Should it cantrip? Hmm, gonna say no; but could be persuaded.

would definately go the modern masters route and make it at least an uncommon.