Soulbound Cards has been a revelation on Splinterlands.
They're called soulbound because they're mostly not tradable, and neither can you directly make profit off them. So you can basically earn them to increase your opportunity of winning, and earning them through chest rewards means that you can further use them to compete and earn or get more SPS. Of course
I don't think they'll ever stop being soulbound, but their in-game value is not questionable, as some of them have become integral to the strategies of minor and mainstream players as well.
I've been getting soulbound cards as rewards for a while now and the legendary SORRIEL THE BALE, a fire card was my first maxed-out legendary, in fact I have a GFL of a maxed-out SORRIEL THE BALE and a regular level 2 foil, and since then, I've come close to more cards.
Although the highest level of any card I've gotten recently is a level seven Gobson Bomber, but I rarely use it as I do not see any use for its abilities.
DUMACKE ORC
Is in level 6 and soon enough, I'll get it to level 7, I'm including it because it's a formidable card in the equalizer ruleset. It halves melee attack by 50% and now at level 6, it has the retaliate ability. It's a neutral card and for low Mana 6, I think it's a good card.
FIRECALLER
The FIRECALLER is already in level seven, I mostly use it for the Martyr ability, because it's more than capable, but in level 7 it has now gotten the ability to do double damage to taunt cards. Although I don't have a level 6 summoner to play this yet, it's one of my highest-level card.
THANE NEWSONG
This is a card I rarely use, but it's an epic and it makes it quite valuable. In level 3 it's added the strengthen ability apart from the inspire ability that it originally comes with. I find it valuable especially when I'm using one of those Earth Gladius cards.
FUNGUS FLINGER
This is one of my most used cards in the game. Although I don't use it yet at level 7. The Martyr ability again comes in handy when trying to boost the attack of my Quora Towershead, it's also low Mana and you can use it in low Mana games. I can't use it yet with its new ability and this is because I don't have a level six neutral or earth summoner
DRYBONE BARBARIAN
This is one of my most influential cards, the retaliate ability coupled with the fury ability makes it one of the deadliest soulbound melee cards. I cannot recount how many wins I've gotten with the new ability. It's a great and influential life card.
Interested in some more of my works