Dragonewt Fist is probably the easiest way of doing it, besides Conflagration. As for Blood, Revelation is the way to go. If you're playing hyper aggro blood they'll probably die before the frog can even do anything.
For other classes :
- Forest : Elf Child May, Will of the Forest, Homecoming
- Sword : Cyclone Blade
- Haven : Themis, Tribunal
- Shadow : Orthrus, Necroassassin, Lurching Corpse, Balor, Odile, Khawy
- Rune : Calamitous Curse, Mutagenic Bolt, Master Mage Levi, Winter's Caprice
Ambush followers are generally understatted, so the best strategy is to further your own win condition while preventing theirs. If you are playing against ambush, chances are its an aggro deck coupled with storm followers and a lot of face damage, so solving a single ambush follower isn't enough. Gameplay wise, keep an eye on the how the game goes, so that you can make the winning plays and avoid giving the ambush too much space to operate. Deck-building wise, tune your deck to not have too much removal (if you're going first, you will have the opportunity to maintain the board and force ambush to trade) unless your endgame is a combo like otk roach or d-shift.
For dragon, the typical ramp into zeus/bahamut/israfil usually blows ambush out if you have lots of heals to sustain through, such as dragon's nest, sibyl and fervor (if you look at it another way, heals are like removing the follower for a turn perhaps). Like Reionyx says, AOEs like conflagration, wrath drake and bahamut are good.
Vengeance is probably the best blood to beat ambush with. You have access to heals to delay the game (if your opponent is playing ambush chances are its an aggro deck) boardwipes like revelation and strong wards like spiderweb imp, veight and grimnir. Not to mention incredible tempo tools like diabolic drain and scarlet sabreur to gain back the board.