Plants vs. Zombies Garden Warfare

This is 100% luck based and can get really annoying waiting for the Yeti to spawn. I found a little trick that makes it quicker to get diamonds (and Vamp kills for that other achievement) by using team revives. I get long winded so I'll try to briefly write a solution then a bit more detail about the Yeti after.

1) Start a Garden Ops solo game on easy and make sure it is private / invite only. Make sure you have at least 3 team revives or to be safe at least one team revive per diamond you need to farm (you / your team can only use 3 team revives / game).

2) I don't believe the map matters but after 8 straight hours of no Yeti spawns I started exclusively playing the Jewel Junction Night map. I don't think this made it any faster but its what I did.

3) The first wave you can see the Yeti is wave 3. So just keep replaying the map to start of wave 3 until you get the Yeti challenge.

4) When I got the Yeti on easy, it would always be a wave of just the Yeti (and his little minions he spawns) and a single foot soldier zombie. You have about 30 seconds to spot / get close to the Yeti to then extend the timer to about 2 minutes. So find the Yeti fast and start shooting and chasing him around the map. He will drop coins, coin bags and sometimes diamonds when you shoot him.

It is VERY IMPORTANT that you do not kill the foot soldier zombie. This is because the Yeti goes away when the timer ends and if the foot soldier is dead as well, the wave will end...that's not what we want. Chase and kill the Yeti then let the foot soldier zombie kill you.

When given the option, use a team revive. This will restart the wave with the same Yeti challenge you just got. You can do this 3 times for a total at 4 rounds of chasing the Yeti for diamonds. If you are lucky, this is enough to get 7.

Misc. Info:

The Yeti you are looking for is the treasure Yeti. I don't believe you will ever get him from the slot reels on waves 5 or 10...only the challenge waves.

I believe the types of waves are fixed. For example waves 1 & 2 are always just regular zombie waves. Wave 3 always seems to be a misc. challenge wave. Wave 4 seems to be a special wave (like all stars or etc). Waves 5 & 10 are boss waves and won't spawn the Yeti. The only wave besides 3 I know you can spawn him in for sure is wave 8. I'd never play that far though,. I found it faster to just keep replaying waves 1-2 to get the Yeti on Wave 3.

Whether you play with 1 or 4 people, you only get 3 team revives and only the person who picks up a diamond gets credit. That said, you will save a lot of time by doing this one solo.

Lastly, I killed he Yeti 3 times in a row for zero diamonds. I have also had a wave where I got 2 diamonds off him at once and also a wave where I got 3 off him at once. One of those 3 seemed to be dropped by one of the little minions he spawns (after I killed it) but I think that was random...they don't always drop them.

Its still a miserable luck based achievement but using the team revives definitely makes it quicker. This approach also works for farming vampire zombie kills. I'll post a solution for that also.

This is just a companion solution to njduke007. This is a complete pain. So i far i have encountered 10 differnt wave 3

1. Break the vases
2. Mini Gardens
3. Zombomb
4. Loot Yeti
5. Mint Garden
6. Hacking ( forgot what the game calls them)
7. speed run
8. Tombstones
9. Cheiftans
10. Unscrathed

So basically there is a 1 in 10 chance of getting the loot yeti but it fells like it's worse than that. After istarted playing the first 3 rounds and quiting out it took 42 times to get the loot yeti 4 times. This can be done sooner but i wasn't always getting a diamond, however the last time i killed him i got 3.

Its also worth noting that you must finish or fail the game to receive credit for the diamonds. If you quit out, it will not count.

Mattynicklin has confirmed that finishing the wave and then quitting also works.

[EASY SOLUTION]

All the other solutions are good, no doubt about it but after i spent (wasted) hours over hours on this achievement, i finally got a nice and cozy solution figured out.
(got this sucker on 360 and X1 now)

This is what you do:

Start a Garden Ops SOLO match on "Sharkbite Shores" / "EASY" / "Private Game"
One the game started plant the garden on the coast, left from the starting point.
(The one with the rocky Arc, used for the Crazy Achievement)

DON'T bother planting anything, just hop on the Arc (Peashooter only!)
or play as the cute Sunflower, hide with her in the back (huts) and shoot anything.

When Wave 3 comes there are 10 possible outcomes:

1. Break the Vases
2. Mini Gardens
3. Zombomb
4. Treasure Yeti
5. Mint Garden
6. Hacking
7. Speed Run
8. Tombstones
9. Chieftans
10. Unscrathed

If anything else than a treasure Yeti comes -> QUIT out and Restart the procedure.
If "Hacking" came and you quit out, it will never come again as long as you restart the Garden Ops.
So the chance of a Yeti appearing is 1:9

If the Treasure Yeti appears, rush towards him and shoot him until he drops diamonds.
He drops them very unregulary... that son of a icy bitch.
BUT DON'T KILL HIM!!!!
Leave him be and jump into the water if his energy is very low or the timer runs out.
So you can take advantage of the 3 garden retries, and if you use one it will be the Yeti again.
So you have 4 tries to get the seven diamonds.
I needed around 5 hours of playing and around 4 tries to get all seven since he drops them at luck.
If you kill the Yeti in your fourth retry, kill him and he mostly drops a diamond.

The diamond counts towards the achievement as soon as you pick it up!