>enemy digs a tunnel to intel through the entire fucking map
>there is nothing you can do to stop him. only guard the tunnel and spend your time on that fucker

I suggest to add an explosive which will have the ability to ruin the tunnels in a small area and make this area harder to dig (or collapse when someone goes in idk).

or you could dig annoying pits for people to fall in

You couldn't dig a pit if the tunnel is at water level... But yeah, the idea is there's a lot you can do to turn it against the enemy. If we get mines, it would be awesome for that purpose.

Filling in corners and creating decoy tunnels can trick other people but there probably should be a faster means provided to fill in tunnels.

Need a faster way to fillin the tunnels?
dig in a load of fake junctions and fill it in with the same colour blocks... :P
But yeh faster way to do it would be a good thing, idk about an explosive though :3.

You serious? Explosions are always a good thing.

I mean a more powerful/a second explosive lol, nades are fine, maybe just give each player 1 or 2 extra nades and give them the power to colapse a tunnel?

Generally I find that quick diversions and block offs are the best way. I must admit there's certainly something dastardly about diverting all that hard work. If I know the digger is persistent I'll wait beyond a block up and as soon as he digs through, he gets a bullet to the face.

If you're interested in more talk about balancing out tunnels by using either cave ins or explosives, have a look here:

http://ace-spades.com/forums/topic.php?id=222#post-3825

There was some talk in particular about mines that were very dark brown- easier to spot on the surface but very easily hidden down in the tunnels.

Well... It would be overpowered if it was given as the tools and weapons that are now... , i mean , if a griefers have the power of TNT... well , you will imagine that.

To be controlled it should be achieved , very hard! , for example in minecraft for tnt you need to kill at least 3 creepers , and killing creepers is a challenge because they will normally explode because people attack them as noobs.

Probably for TNT you should have like 50 points or something like that.

Because having TNT for all the players will introduce a new level of griefing to AoS