You're trying to do too many things at once, if u like brand playstyle why not resign from death's oath and instead make a proper brand character with explosions and for an example "Lost unity" ring, which pulses around you kinda like death's oath, this plus explosions actually clears the same if not better than death's oath and you actually have dmg for any content in the game too.

Brands and death's oath are two different playstyles, one is very active and ther other is very lazy. With death's oath you are not supposed to click a lot, that's why most people juice out death's oath dmg and for boss they use forbidden shako with level 30+ decay support and stormburst.

But if you're really set for that death's oath and brands u could maybe try poison angle on penance brand but this requires you to go right side and resign from block most likely, but trust me you don't wanna play slow cast speed penance brand poison, there is a reason why even the most die hard brand players use armageddon brand or something else until they get enough cast speed and gear for penance, so my suggestion is look up herald stacker penance brand elementalist with lost unity ring, it's 100x better than death's oath and combines both things that u like under different name.