No idea if it's any good (probly not) but it's worth a shot

Either:

Kamikaze (unit)
Duration: 5 turns
Price: normal merc cost for that unit + 20-25g
Details: unit looks and acts like a mercenary unit (same stat drops and what not) but when the unit would normally disappear after 5 turns, it instead makes an Artillery (special card, not unit) effect on the surrounding hexes. Friendly-Fire possible

or

The Clock is Ticking
Duration 5 turns:
Price: ???
Details: Turn one unit into a mercenary with 5 turns to live. When its turns are up, the same thing as above. Friendly-Fire possible

Any thoughts? Dont be afraid to tell me it sucks

bubbels i find my ideer better with kamikaze unit with lest cost but can only tarked one unit """
not any read my ideer i see ""
i think by the mechenary the time counter must be a littel bit less because the efeckt bring you not any when you has a not situation with a 5 turn counter and on special units it bring more to dbuff and kill them as to wait 5 turns

I like the underlying idea. How about this:

Name: Last Laugh
Duration: Permanent (2 rounds)
Cost: 50g?
Text: Give a unit you control a bomb that is placed in the same hex that unit dies. After 2 rounds this bomb explodes, dealing 65-85 damage in that hex and 50% of such damage in adjacent hexes.

I think we need to stay away from suicide bombing style cards...I'm pretty sure that threads have been locked when that was brought up before. This way you can get a similar "flavor" of card (which sounds fun).

Rothmorthau

true, we definitely should. And I like that. The mine should definitely be like Land Mines (hidden normally, but visible to enemy with a vision buff). And should also have friendly fire