User blog comment:StripperRiven/Sierra, The Eternal Flame/@comment-7481207-20131004095201

You might want to rebalance the ultimate a bit, its base damage without kills or assists is ok since it is a global dot with possible increased duration, but the scaling is already really high even without any duration extension. The cooldown is also far lower than Karthus' ult which it is similar too.

And less relevant, the maximum damage of the ultimate can be higher if any enemy champion has picked revive and is actually dumb eneough to use it within her ultimate.