A mirror of Underwater Mine for red/green. Because these are the colours of revolt, this effect has a little more comment utility in these colours. But the specific effects aren't as good, even with the cost coming down to . I don't think a telegraphed Battlegrowth for 3 mana is going to excite anyone, even if it comes with a Lava Spike.

Maybe the thing to do is actually make the green effect match the blue effect of Underwater Mine and just draw a card. The (Green-blue archetype) is focused on drawing cards, and a cantrip Lava Spike that also triggers revolt is more interesting.

I don't like that the flavour of this comes across less clearly than Underwater Mine though.

Don't step on that land mine! It'll make you stronger; and explode that guy over there!

Wait...

Yeahh, that's what I was getting at :)

It's tricky. With red-green having the revolt theme, I really want a red-green artifact that mirrors Underwater Mine (which I am happy with). Given it's red and green, the name "Land Mine" seems pretty natural, although there aren't actually any land mines on-screen in the series. I could make it a Claymore mine, which are seen.

But the problem is that the Underwater Mine really wants to deal damage to an attacking (or blocking) creature, but then it looks rather wrong for red to just deal damage to any creature.

FWIW I think it would be totally ok to have an underwater mine that damages attackers or blockers and needs R (or is just colourless), if that's what would help the set. I agree having U involved is persuasive, but I don't think it has to be that way. Or maybe try to distance this card a bit from underwater mine so it matters less how it compares, I like the symmetry between them but I don't think it's needed if it's inconvenient.

Yeah, maybe that's the way to do it: have the underwater mine be one of these inefficient colourless damage sources like Scalding Cauldron or Springjaw Trap, which still works in red or green Revolt decks, and get rid of this one. That makes sense.

Or now I think about it, it could be something like

Underwater Mine If was spent to cast ~, draw a card. ­ or , : Deal 3 damage to target creature [or target attacking creature, or target attacking or blocking creature]

If you want to reinforce the "underwater" "mine" flavour. Obviously both bonuses and costs could be tweaked to adjust what archetype it's best for.