Ast cards should stack.

[Kurando]

snip

Only partly correct, many effects do not stack either but we are not talking about DOTs. Chain Strat, Foe Req, Contagion, Ruination, Addle, Feint, Radiant Shield, Hypercharge, Trick Attack, etc are examples of things that don't stack (usually only reset timer) because if they did they would be very OP.

A good AST knows how to work with another AST, simple.