What sucks about this, is that Magi’s Spark is still not fixed with Arcane Missiles. It will only echo the first missile hit, and not the rest. It was allegedly fixed back on August 13th, but it only does the echo from Arcane Echo for ~9k a hit, and not the actual hit to copy into Magi’s Spark.
https://warcraft.wiki.gg/wiki/Magi%27s_Spark
Which means, if it hits for about 90k, instead of echoing 90k, it’ll echo 45k, and the other spells (blast and barrage) at 50%. Burst will go down, but sustain will feel better with the increased damage to arcane blast and missiles.