Use any of your usual farming decks, but replace some cards with forced ceasefire (set it a turn before you're going in otherwise it will be destroyed by his Trap Master). This is to prevent him from activating Ready for Intercepting on your vassal.
i've been trying for AMA too.. Atleast 40 tries with 6k assassment and i've gotten 2 sr's.. 1 Dark eradicator Warlock and one PRISMATIC diffusion wave motion -_-
arrow wont work, arkana will flip your vassal when you target it. im using elements with uforoid and uforoide fighter, darkflare and wingbeat for clearing the backrow. sanga and guardian will give you light and dark for darkflare. other option is a classic dino fusion farm with piranha and 2 gift of the martyr. should give 8k with enough glossy cards.