Devil Dragon

Level 70 isn't too far off, considering the exp required to reach it is considerably less compared to other monsters.

Though leveling up can be pain when you have the right evo materials but not max level..

When you feed a monster with something that has the same skill, you only have a chance to skill up. it is not 100%

I agree w/ you on how frustrating it is to skill-up the monsters. P&Dx says in the "Articles" tab that the chance to skill-up is only 10%, and that you should _never_ try to do so outside of a "2x Skill-up" event ... which means it takes [on average] 5 fed monsters to get 1 skill-up. So for a Devil Dragon w/ a max skill level of 16, it will take approx 15 x 5 = 75 other Devil Dragons fed into one to skill it up. AND if you merge two monsters who each have a skill-up, there is only 20% odds that after will have 2 skill-ups. AND when leveling up the monster to one w/ a different skill it starts all over again at skill level 1. I really don't understand why you can merge like monsters and get Awakening skills at 100% chance, but not the same for skill-ups!? AND if you Evo or un-Ult Evo, the Awakenings stay. So if you want to skill-up your Chaos/Cyclone Devil Dragon, you will have to feed your Lil' Black Dragon 680,039 EXP (or an easier 623,949 EXP into Devil Dragon) through two Evos a total of 25 times to get a cool-down of 10 on their Hell Ball skill. So hypothetically if you did have fodder that totaled 17,000,975 EXP (and all the Evo material) to feed your Lil' Black Dragons, why would you do that instead of max level your top 4-5 Dark monsters??

All you can realistically do is find which monsters require easy to obtain skill-up fodder monsters (Heart Converter series, and all of the bi-weekly dungeons) and spend time on those you need.

If anyone at GungHo reads this comment, I wish that either (a) skill-up levels stayed when Evo a monster, (b) skill-up odds were higher (50%?), (c) skill-up odds varied by monster ... yes I know that Hera Descends is farm-able for Gravity skills, but then Chaos/Cyclone Devil Dragon is not, or (d) skill-up odds varied by level of the base monster ... above level 80, should have 100% skill-up odds, lv 60 = 80%, 40 = 60%, 20 = 40%, <20 = the horrible 20% odds that are at present impossible for most monsters (during "2x Skill-up" events).

Or the fact she has that resurrection skill in that dungeon despite being a heartbreaker.
Still can't get over how many times I tried and failed due to that skill..

Like Valkyrie being the "Goddess Descended", but not a God. Always wondered why she doesn't get a God sub when ult evod (hint hint Gung-Ho)....

You have to do an "Evo fusion," which is different than the power-up fusion. Only does an ult-evo go in the power up fusion.