So the Tumbleweed Familiar is back in the Marketplace. It grants a 10% Dodge familiar benefit. According to Lucy, it does not stack with a handful of spells like Guardian Circle and Illusion Benefit Neza. However, I recall someone mentioning that these dodge buffs are automatically overwritten by Myrmidon's Skill (stat check). Does anyone know if Tumbleweed will offer a bonus beyond Myrmidon's (especially since it falls under the familiar buff category)?
Myrmidon's Skill is now an AA focus and will stack with spell and item (worn) focus. The DodgeSPA is a combination of all 3 and is used in the dodgechance calculation. The typical item focus is the range slot, Improved Dodge. Your spell focus is probably Illusion Benefit Neza (for most people). Tumbleweed will not stack with Illusion Benefit Greater Jann, which includes 20% bonus to dodge.
Here's the dodge chance calculation. Highest of each (AA, item focus, and buff) are used. As Menown said, Myrmidon's Skill is a passive AA now, so it no longer competes with your buff effects.