Finally i was able to max all legendary rebelleion reward cards. As you can see on the card numbers Syrenth was the last and it took me quite a while to get the last needed card.
1. Gallicus
There are rulesets where Gallicus is a key card (ranged only, little league ...). It has a good value for 4 mana.
2. Syrenth
Syrenth is also a key card for ranged battles. But this time more for the high mana battles.
3. Death Ranger
Death Ranger is again a good ranged card for low mana / little league. The scavanger ability can lead to victory with the correct line up.
4. Chaos Battle Mage
This card is a quite good card on no magic rulesets, beause of the pierce ability. Since it is neutral it has many use cases and can be even used with i.e. yodin.
5. Emberguard
Emberguard is a okay red magic card. Due to it's high mana costs there might be often other cards you would play instead.
6. Seargant Grauzral
Grauzral is not a bad card, but with all the nice alternatives on blue, i actually tend not to play it. Maybe it is good in silver / gold but on diamond i guess it is not played very often
7. Warborn Chieftain
Chieftain is very similarto Grauzral, i do not meet him in Diamond and tend also not to play it. It has a lot of abilities, but it seems the combination of the abilities to not fit well enough to make him a key card
8. Surly Drunk, Endless Gibbon, Blackmoor Jinx, Frigid Wolf, Griftzi
I think all these 1 mana cards are very similar, they all have a ability to attack not only from the first line. Of course they will be played to fill up the line up. But i am missing another useful ability on them like for example on the 0 mana chaos league legendaries. Or older cards like flame monkey, creeping ooze, brownie - i think most of them are better (and the old cards are not even legendary ...), because they can help the whole team and not just attack.