This may have been made known previously, but I will restate it in case it has not been: (I assume the devs are aware of this, so I am mainly posting to inform other players that may not already know.)
Skill tooltips are bugged to display incorrect values on Non-Dot abilities when Champ points are placed in the Thaumaturge star. The tooltip still reads it as if Thaumaturge was increasing all spell damage (as it did before TG). This inflates Non-Dot tooltip numbers, providing false information to the player. I did some testing on the PTS (since I didn't want to burn a bunch of gold on Live) using Crushing Shock and Lightning Flood. If someone else wants to double check on Live, feel free to post confirmation. If ZOS has mentioned this before in a Known Issues area, I must have missed it.
Anyway, here are the numbers I pulled, just spamming down mammoths on PTS:
0 in Elemental Expert / 0 in Thaumaturge (0% increase/0% increase)
crushing shock - 1626 (true dmg from combat log 1572-1826)
lightning flood - 1826 (true 1826)
100/0 (25%/0%)
cshock - 2160 (true 2089-2102)
lflood - 2424 (true 2425)
72/28 (19.9%/10.3%)
cshock - 2248 (true 2002-2012)
lflood - 2523 (true 2524)
50/50 (15.4%/15.4%)
cshock - 2260 (true 1928-2002)
lflood - 2537 (true 2537)
28/72 (10.3%/19.9%)
cshock - 2248 (true 1842-1943)
lflood - 2523 (true 2524)
0/100 (0%/25%)
cshock - 2160 (true 1671-1762)
lflood - 2424 (true 2425)