We don’t know if it can drown
We do know it can take fall damage though. But with 500 hp, dripstone spikes might be helpful
If it can’t drown then just open a nether portal and lure it in since the portal makes noise.
As long as it can’t close the portal passively, then that’s usually a good way to remove problems.
What if the amount of wardens that can spawn is infinite?
All that obsidian placing would trigger a lot of sculk sensors, therefore a lot of sculk shriekers, therefore a lot of wardens
On day 1
Warden 1.18 Farm (200+ Drops per Hour!) - Easy Build
That’s literally what’s gonna happen though 