Post trimmed for redundancy with previously expressed comments.

If AoE farming and doing nothing else when magma is down, it's better to drop 5 magmas.

If instancing/casting other spells during the time, ToW + 4 magmas is much better.

I don't really AoE farm, so I just changed my fire totem drop to 1 ToW + 4 magmas with the 3.0.8 patch.