This is all about the end game and being able to turtle, but up until that point the fire ring allows a player to boost production by like 300% or add an additional 23 exp per second to reach a player's final cards. I am not sure about the other heroes, but with the bonus at the fire pit the Aztec hero has like 7000 health. Immediately after a battle, where your Skull Knights floored the enemy, they will all likely be hurt (not killed, just damaged) but with the fire pit these units can be healed in a matter of seconds (16% per second healed). If an Aztec player is about to be attacked he can quickly switch to have his defenses increased by something ridiculous like 238%, with other shipment bonuses and upgrades a single piece of wall can have like 60,000 health.

All of the other units at the Nobles hut get the same upgrades with the exception of the splash damage, but each unit does receive another bonus. Add a supply shipment to increase their attack (2x), hitpoints, and defense, plus an additional point to their splash damage (making it 3) and a card to increase all building damage, a small group of 20 of these guys can wipe out 60 or more other units easy and run circles around a castle or two with minimal losses. A player familiar with the bonuses at the fire pit can quickly train an entire army of skull knights for free, and then boost their attack by 38%. If allowed to turtle the Aztecs become completely invincible.

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