Basically you make them attack you, block with your walls and then deal damage to their creatures (and directly to them with Greatbow Doyen). Taunt and Siren's Call are both excellent since they force your opponent to attack you and essentially give you free damage. Polymorphist's Jest will let you kill anything with one point of damage regardless of it having shroud or indestructible.

Example:

Play Brigid

Play Siren's Call next turn to force all creatures to attack you

Play Polymorphist's Jest, tap Brigid to deal 1 damage to all of them, everything dies.

Against a big army, if you have Greatbow Doyen out and you use the aforementioned combo, you can instantly kill the other player with just Brigid if they have enough creatures.

Another example: