From LOTR-TCG Wiki
A bomb is an informal game term for a strategy—invariably a Shadow deck strategy—that patiently builds up the perfect hand and support area before "going off" and winning the game all at once. Such decks usually use a some sort of combo to ensure they get the most value possible out of that one perfect turn.
Some example bomb strategies:
- Overrunning the Free Peoples player with a swarm of many minions, or perhaps a larger-than-usual number of very strong minions. Generally, swarm decks are only called "bomb" decks if they somehow play many more minions in a single turn than is normally possible.
- Decks that corrupt the Ring-bearer with many burdens all at once. For example, playing multiple copies of Lost to the Goblins (1R189) in one turn, after you've filtered out almost all of the Free Peoples cards out of your deck.
- Little Snuffler (13U52) decks that kill the Ring-bearer in region 1 in the Shadow Phase. This is weak variant of the Ninja Gollum deck.