I've personally been using something similar to the Piranha deck to farm Ishizu. The deck list is below. Pretty simple logic of using Leotaur and Warrior to keep clearing the board (clear Necrovalley if and when needed). You want to summon Blue Eyes as soon as possible (Replace Sheep if you have 3. Kaiba hasn't given me my third yet). Once Blue Eyes is down you can just keep clearing with it and set Overwhelm to prevent Rite of Spirit into a tribute summon (Sphere Kuriboh is a back up). When summoning BEWD tribute Leotaurs if you can, if not then just make sure 2 are in the graveyard via 7 card hand discards. You will want 2 Shards of Greed at least to keep up with the GK Recruiters she has so you can get down to Cards on Brink before she decks out. Once you get to the point of deckout she should have only one monster on the field (just set from her previous turn). You can then use a twister/de-spell to take out the Necrovalley. Special Summon Akz The Pumer. Use Riryoku BEWD->Akz. Then Polymerize to create BEUD. Use Riryoku BEUD->Akz. Now use Akz' ability to double its attack and discard the last Leotaur kept in hand (or another Beast-Warrior if you don't have 3 Leotaurs) and Akz will have over 10,000 attack. Use the 2250 BEUD to clear the set monster and attack with Akz for victory.