Board Thread:News and Announcements/@comment-25404524-20171206094918/@comment-27661991-20171207004205

Yeah, the cost progression basically continues. Unless you've basically got a bunch of gold and food sitting around doing nothing anyway, there's little reason to start feeding monsters...

...except, that you get bonuses once they're above 15!

https://i.imgur.com/enoqGkL.png

( The specific bonus that was received was food for an Ethereal on Ethereal Island. )

Just to add some stats for an Ethereal on Ethereal Island (I'd imagine it'll be in the guide soon if not already):

Jeeode, 100% happy lvl 15 = 48/hr, 300 max feed to lvl 16 = 4 x 245,760 treats lvl 16 = 50hr, 315 max feed to lvl 17 = 4 x 368,640 lvl 17 = 52/hr, 327 max feed to lvl 18 = 4 x 552,960 lvl 18 = 52/hr, 337 max (no, no typo - no /hr increase) feed to lvl 19 = 4 x 829,440 lvl 19 = 54/hr, 344 max feed to lvl 20 = 4 x 1,244,160 lvl 20 = 54/hr, 347 max (again, no typo)

That makes leveling Ethereals up to level 20 a matter of whether or not you can check every 6 hours and 20 minutes or so. If you can - just keep them at level 19 (until you've got food to burn through). If not, then level 20 will make more sense anyway.

As always with leveling up Monsters, leveling multiple up to a lower level is still way more efficient than leveling an individual Monster up to a higher level.