I wonder how "Gain 0 life" would interreact with Cleric Class? XD

But alas, that can't work. Had to do a little digging, but rule 119.10 disallows it. Otherwise, Lifelink for 0 would have triggered far too many things. ;)

I'd prefer it if this was ": Gain 0 life" or "Kicker " (with no kicker text) or something. But those would have edge case interactions (Angel of Vitality wouldn't see it, but you could arrange for it to trigger Ceaseless Searblades and Roost of Drakes respectively), where this is most blatant about "I'm including these symbols for no reason at all", so... sure.

It's a worse Memnite, so sure

This amuses me much more than it should.

It's probably ok power wise in modern magic? I mean, Crimson Kobolds are sad, but they were mostly a joke at the time too'; the 'forever recycle a 0-cost' ship already sailed before they arrived.

Gosh, yes. Literally the only penalty is that you cannot play it on turn one. So long as you have another land it's just flat mana ramp.
And that's not even getting into the potential of "And in response, I drop a secret cove and now I can afford..." Even if I was playing another colour, even if it sacrificed itself at end of turn it's still a +two-mana ritual.

As it is, this is way way too good. I get that you seem to want to play with fun effects on lands; but there is, sadly, a reason why their effects are very weak. Which is that there's almost no cost to putting them in your deck, since they replace land slots you already had to dedicate, and they don't cost any mana.

This seems strong, like super strong, I cannot fathom a reality where this isn't broken

As a land that does equal damage but doesn't tap for mana? ... yeah, I probably would run that in some decks; though it would want to be rarer than this because not all that many decks would want it.

Letting all your lands do it forever is crazy powerful. At least it doesn't stack.

Well, it doesn't tap for colorless, so it costs a card and a land drop. It also doesn't hit creatures, but I agree... this card would have been playable if the ability only worked on itself. Giving the ability to all the lands is murder.

Wowee. Aggro decks love this so much. I get to Earthquake us both every turn without using up a card?

I like it too. Only problem is that as a land that doesn't produce mana, it's against current guidelines. But I do completely get that that's the intended cost.