Top 5 Units
1. Ruler of Crest / Eskatia - Even if lawtia didn't have so many units that become ridiculously powerful at night she'd still have decent stats and abilities for her level. The fact Lawtia does have said units means she's the key card in the ridiculous powerful Endless Night deck. She's not for every deck, but for the deck she belongs in theres arguably no unit more essential to its theme, and quite a powerful theme it is.
2. Sylph - Special mention should go to Undine as well, but Slyphs superior speed plus the fact she doesn't rely on your opponents units (Undine isn't really that great against say Refess who are often slower then you anyway) gives Sylph the edge. The ability to pretty much make any unit of your choice go first for the turn is absolutely incredible. The ability to then hide in the back dealing some extra poke damage every turn (and at a decent speed too) is just icing on the cake. I do believe I've seen her used in every clan, and used effectively.
3. Salamander - Here's another card I've seen splashed in many clans. At 1 sp its a cheap way to quickly finish off anything with 10 or less hp (and it ignores defense too!) but its usefulness doesn't stop there. Once it hits the field it can hide in the back and deal a whopping 30 damage every turn! Refess can't muster that much attack on their level 2s or nearly any of their level 3s, let alone level 1s. Sure it dies easily but with that much range, getting to it can be quite an ordeal for an opponent. And again... its level 1!
4. Shade - What can I say, theres alot of really powerful level 1 cards in the first set. Like Sylph and Salamander, Shade has an absolutely amazing open ability, and yet can continue to provide support from the back lines once it hits the field as well. If you manage to drain away 1SP, you basically got a unit for free. If you manage to drain 2 SP, its as if your opponent payed you to play it! But SP advantage aside Shade is also a great way to prevent your opponent from using those high sp abilities or saving up for those high level units. He can really control the flow of a game. Pretty amazing for a level 1.
5. Brave Soldier - It was really hard to choose only 5 units cause so many units are the back bone of top strategies, but I had to choose so in the end I gave the last spot to Brave Soldier for being the backbone of the infamous Brave Panther combo. As just a normal unit he's nothing special, mediocre stats for a level 2 and a really high rank up level restriction. But if you can rank him up, whether the hard way or more likely via panther soul, he becomes an absolute monster. 50 hp is unheard of for level 2s, even Refess level 2s top out at 45. 60 attack is ridiculous for any unit of any level. In the first set (and including ex cards) 50 attack (60 with panther soul) is the second highest base attack behind only Death Incarnate / Proposition. 3 AGI (4 with panther soul) means he's either attack first, or near first, and his slash ability means if you're opponent stacked his front row with units he can prepare to cry while he watches them all close in a single action. He requires a little extra work to get going, but once you get him ranked up few cards are more feared on the battle field.
The bunnies of Lavato have special abilities, like 'Action Skill: Make Carrot Disappear.'