Tower Shield reduces 60% of true damage instead of 50%.
Also reduces 35% of true damage from Super-Criticals instead of 10%.
Acts as a cheaper version of the Phantom Ascent trophy upgrade. If you have both, your defense charm gains +1.5 Damage, and Phantom Transmit gains slight auto-aim if looking near a player.
Your Critical hits have a 75% chance to become Super-Critical instead of 50%.
Furthermore, your Super-Critical hits deal an extra 20% true damage.
Your Critical hits have a 100% chance to become Super-Critical instead of 75%.
Furthermore, your Super-Critical hits deal an extra 30% true damage, which is additive with the previous bonus.
Upgrading costs an extra 0.5% less. This applies even in Hardmode.
Your clicker gives 2x as much +1, for a total of 128x.