Fiesty
washed up tink
Ive already answered this suggestion before, arenas would be a great thing to get to but at first Duels I believe would be the best choice. The idea of Arenas to people who dont play arena is kind of scary because no only do you let yourself down when you dont preform you let down a team mate. as people Progress I will urge for people to move to arenas as there skill will develop the result.
You have to take a chance at failure before you can progress. Weather its in a arena setting or just spamming duels the risk of failing is always there. In many cases this ends up making players better.