I think I made a functional tank!

[SangoProduction]

Shield Sphere's Active Defense increases your shield's bonus to AC by +2 (+BAB/4). Cover Ally lets you use active defense for allies, which presumably gives them the full bonus of your shield, not just the +2 AC.... It probably just means the +2 AC. Damn it. Well, I'll assume it means the whole thing.

We'll assume a level 10 Conscript. This grants us 15 Talents. Also gives a +9 AC between Active Defense, Shield Expert and a Noqual Tower Shield. Give the shield +5 enhancement (easy by level 10) for +14 to start off from.

Let's talk purely sphere talents. Feats could be spent on whatever non-primary task they want, or speeding up the progression on this.

Martial Tradition of Shield Master (no use of custom traditions, which are even less concrete than SoP's, thank god). This grants us 2 Shield sphere talents (base sphere and Cover Ally), Shield Proficiency (very useful), and Tower Shield Mastery (removes attack debuff, not that it matters).

(lvl 1) Deflecting Shield...could be read as only working for you, and not transferring with Active Defense. If it does, great. It's still great. Just not as great.

(lvl 1) Expertise Defense lets you Cover Allies and yourself by using your focus. Not certain if it's better than just stacking AoOs.

(lvl 2) Jarring Block for the disarm on block.

(lvl 3) Blockade to stop pesky AoE.

(lvl 3) Shield Expert [Equipment]. +1 AC

(lvl 4) Guardian (Challenge). -2 (-4 at lvl 8) to hit allies, +2 to hit you. That's a difference of +6 to hit.

(lvl 5) Mass Challenge. Challenge all enemies to get that debuff going.

(lvl 5) Iron Wall. They now have 20% miss chance for hitting your ally.

(lvl 6) Durable. -2 to ability save DCs if they don't include you. (Yay for Blockade.)

(lvl 7) Defend Other. +4 AC...for one attack...as an immediate action. Ew. But it contributes to the goal.

(lvl 7) Cold Iron Call. -2 to spell save DCs if they don't include you.

(lvl 8) Expanded Guardian (Patrol). Buffs many Guardian talents (like 50% miss chance against allies in your range).

(lvl 9) Assist. Aid Another for +2 to Saves, AC, or attack rolls, for the cost of AoOs. If you were a Halfling adopted by Gillmen (traits), that goes to +5. Ring of Tactical Precision, +6. And with Benevolent +5 Shield, that goes to +11 (though only on AC).

(lvl 9) Swift Guardian. Improve Action Economy.

(lvl 10) Swift Reflexes. More AoOs. More Assists.


So, overall, we give allies:
1. +14 AC (+25 on spending aid another, +29 on immediate action), which, with base 10 AC, gives a >50% miss chance up until CR 17, for most creatures. [if we don't transfer the whole shield bonus, just the active defense bonus, reduce the numbers by 10]
2. -2 to save DCs against most things (+6 to saves with aid another)
3. Reduce enemy to-hit by 4
4. 50% chance to be missed by attacks.
5. blocking a cone shaped area of AoE.

You get basically none of that. But that's fine, as you want to be the one actually tanking the hits. Good thing you didn't spend *all* of the resources on being the only one vulnerable to attack.

[stack]

You only give allies the active defense bonus, not the full shield bonus plus active defense.

You probably want armor in there somewhere unless you plan to tank via HP (berserker THP helps a bit) and/or using punch block for active defense.

Using a lot of AOOs (1 per use of active defense and 1 per use of assist), so muscular reflexes on a strength build or combat reflexes on a dew build would help out a lot.

Need to keep focus to use cover ally. Blockade, swift guardian to patrol as a move, etc. may compete for focus. You will likely want a talent to streamline getting focus back and to spend a feat for a second focus.

Halfling raised by gillman is unlikely to fly at most table. Excessive aid-another optimization is generally prone to receiving objections.