Board Thread:Questions and Answers/@comment-112.196.179.182-20170529090042/@comment-31529160-20170530110150

In depth explanation :-

Silver abilities:-Normally the very first abilities of every fighter, they're the weakest in terms of damage and has the lowest xp cards needed to train them.They come in xp cards of 2,4,6, & 8

Yellow abilities:-These are the second weakest abilities and slightly easier to train compared to silver abilities they are in 4,8,12 & 16 xp cards

Purple abilities:-Being one of the strongest/easy to train abilities, they come in 6,12,18 & 24 xp cards.

Orange abilities:-Only the deadliest and strongest abilities comes in the form of orange abilities and it also encompasses Legendary & International abilities.They're exhibited in 10,20,30 & 40 xp cards

NB:You need 3000xp to max an ability and for every matching ability aplied u get a bonus of x5 per unit card.With this info you can make a rough estimate on the difficulty level on maxing abilities based on their rarities :)