Crusaders

I find crusaders tend to lack the HP necessary to instantly kill an AOE-heavy hero (Sarky, Merlin, etc.), but they can do quite well against Lancelot. Lancelot procing once against a crusader squad often kills all my crusaders but kils the Lance too. What do you use crusaders for? 

Also, I stil haven't solved the dilemma of what would happen if Seamas got crusaders.