So, the Warmogs change on PBE (1100 Bonus HP instead of 3000 Max HP) in theory wouldn't effect Ornn much. After all, Ornn typically hits 30000 HP by second item, which is the earliest you'd take it...

...If you aren't insane.

But, let's say for a second you tried to build Warmogs before your mythic.

With just Warmogs and Doran's Shield, you would have 880 Bonus HP, multiplied to 968 Bonus HP. Which means, you'd only need 132 bHP to activate the passive.

But, you can probably supliment this with overgrowth, the health shard, and grasp of the undying.

Now, I am not 100% sure that you'd hit 1100 the exact moment you hit Warmogs. For one thing, any Champion you'd want to rush Warmogs against would be less likely to proc grasp.

But, if you could time or right (or at worst just buy a ruby) you could wind up getting a Warmogs Armor during laning phase.

Basically. Garen can kiss my ass.