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.
@Frive101 - Replacing Leotaur is pretty difficult. The only current option would have to be Battle Ox. With 1700 attack and no Necrovalley it can deal with everything except for a defense position Priestess. So it's a little risky, because if you can't kill that she might then be able to summon Visionary or Oracle.
@Anonymous - In terms of Riryoku, nothing can replace that loss of 1500 points :(
How come I cannot take bewd out of my graveyard to gain the ATK? Everytime when I have no cards left and do the ritual summon, I cannot remove bewd from graveyard.... How can I trigger the effect?
Yea.... I'm just lucky like that. But the idea is there: Bounce back or destroy the enemy monsters while their field fills w/ Jams. Now the monsters used to do so, that's unfortunately up to you because Duel Links doesn't have too many Return monsters right now. :/
I'm also happy with this deck and will attest to the average 6000-7000 duel assessment score as long as you do it right! To the admin of this site please UPDATE Ishizu farm deck with the deck posted above by an anon! Don't be lazy!
12 wins 0 losses so far, I would say this is a pretty consistent farming deck. Yes the visionary can have high attack, that is why you bring last day of the witch, in case you are not able to set a JBM. Its pretty solid IMHO :)