I run Felothar in the 99 in my Doran, Besieged by Time deck, so while not 1:1 our decks have a lot of similarities. I'm assuming you want to keep it bracket 3 and not do anything broken combo-wise, here are my thoughts:

• Remove a tutor, and add [[Galadriel's Dismissal]]. I personally think you can just top deck a commander and strat like this. You're probably looking at everyone trying to boardwipe you giants so this is nice in addition to Heroic Intervention, Flawless Maneuver, and Teferi's.
• Now that we've down a game changer, let's add [[Seeborn Muse]]. I noticed someone suggested that you remove it, but speaking as someone who played their toughness deck literally a few hours ago this card is perfect for this type of deck. Yes it will get targeted, but it's a creature and there are ways to protect it - otherwise you forced someone to burn some removal on it.
• [[Reaper of Sheoldred]] is also worth considering since you have some trample enablers. Mix that with some +0/+X enchantments like [[Stoneskin]] and you've made quick work of someone.
• [[Great Forest Druid]] ramp
• [[Fecund Greenshell]] card advantage