WMD
SDI advancement has progressed dramatically. This has made all WMD worthless. Until recently. Technology is theorized to be able to come up with a signal which prevents destruction of warheads. This has yet to be actually researched very much. At tech 10, you will have access to arm silos with that destruction-preventing signal. At tech 30, you will be able to produce another signal which completely jams detection of warheads, making stealth strikes reality.
Silos cost 25 income each.
Funding WMD project costs 200.
Building a WMD warhead costs 15.
WMD are completely player-personalized-within reason. By that, I mean you can range it from nukes to bioweapons to whatever it was Sone used on his huge PB strike against the demons in SOM3. Don't be rediculous with the creativity. Warheads will destroy 1 province; and will destroy x% of an economy, x being your tech level. The provinces affected will take 1x, x being the launcher's tech level, turns to clear of hazardous materials.