What is the loading screen border based on?
Your Highest Rank That Season
Or current rank
If so should I wait to play my promos before the season ends?
Your Highest Rank That Season
Or current rank
If so should I wait to play my promos before the season ends?
Loading screen border is based on the highest rank you were at the end of the season. For example, if someone was Plat 1 solo queue, Gold 3 5v5, and Masters 3v3 they would have a Master tier border. See Live2LetDie's post below.
Also, you should never wait to play your promos. The faster you do them the faster you know how much you need to climb (if you want to).
Lord that is actually wrong now. Your team based rank is completely separate from your others. Aka if your silver 3's, plat solo, master 5's then you have a silver boarder in 3's, plat in solo,master in 5. In s3 it use to be whatever your highest rank was that was your border but they changed it. I remember grinding 3s to get victorious Elise haha
I believe it's based on highest. I've seen streamers who have a challenger boarder but their last season ended in masters/diamond.